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Subject: [comp.os.386bsd] BNR/2 derived BSD for PCs FAQ (Part 4 of 10) Newsgroups: comp.os.386bsd.announce,comp.answers,news.answers From: burgess@cynjut.infonet.net (Dave Burgess) Date: 13 Nov 1994 10:41:44 -0600 Posted-By: auto-faq 3.1.1.2 Archive-name: 386bsd-faq/part4 Section 3. (Kernel Building and Maintenance) 3.0 System Internals One of the interesting aspects of *BSD is the fact that it comes with the complete source. This allows you to make changes to the system, recompile, and test out your new ideas. This section of the FAQ describes many of the different aspects of this endeavor and common problems and pitfalls that are encountered. Kevin Lahey provided the substantial portion of this section. You can contact him via E-Mail at (kml@rokkaku.atl.ga.us) or contact Dave Burgess (burgess@cynjut.infonet.net). 3.1 Kernel 3.1.1 How do I build a kernel? The kernel can be compiled in a variety of ways to support different devices and configurations. Compilation is controlled by a config file that specifies the characteristics of the kernel. A set of different config files is located in /sys/i386/conf or /sys/arch/i386/conf. The configuration file names are in upper case. To build a particular kernel (in this example, we use the GENERICISA configuration file in NetBSD or FreeBSD): % cd /sys/i386/conf % config GENERICISA % cd /sys/compile/GENERICISA % make depend % make If you are using 386bsd 0.1, you'll need patch 1 from the patchkit to get the compilation to work, because the version file isn't correctly included in the Makefile. In NetBSD, since there are multiple architectures supported, there is an architecture line in the middle of the path to these files. See the build.kernel script in section 3.8 for more information. 3.1.2 I want to do one of the following things: * add a device not in the distributed kernel (third com port, additional disk or tape, line printer driver, etc). * use a patch from the net or the patchkit to fix a kernel bug. * add another swap device. * recompile the kernel to remove extraneous devices so that it takes up less space. * configure more pseudo-terminals to allow for more xterms or network logins. You're going to have to recompile the kernel after you modify the config file. See section 3.2 below for more information about the config file in general. 3.1.3 I don't have the source distribution -- how can I rebuild the kernel? There are reference sites available, as well as the 'good net-neighbor' policy, whereby you could make arrangements with a net neighbor to use a large local machine as a Network File System (NFS), or allow you to compile a new kernel on their machine and transfer it to yours. You can also ask for help from comp.os.386bsd.questions if you get stuck and cannot make any headway. 3.1.4 Now that I have a kernel, how do I install it? Your kernel is called /386bsd or /netbsd. Copy the new kernel from /sys/compile/GENERICISA/386bsd to /, assuming that it is in that directory. This is relatively straightforward; there are a couple of things to remember, though. First, if you really screw up the new kernel, you want to have something to fall back on, so be sure to save /386bsd to /386bsd.old before copying in a new kernel. Second, if you just copy the new kernel over the currently running kernel, funny things can happen. Be sure to move aside the currently running kernel before copying over the new one. There are folks that have reported that overwriting their current kernel has never caused them any real problems. On the other hand, if the old kernel was working and the new one doesn't, and you have made changes that require that old kernel, it should be available to the system, and saving it to /386bsd.alt or /386bsd.old are reasonable things to do. If you are really paranoid, you can mount a new fixit floppy and replace its kernel with the one you just built, and then boot from the fixit floppy to make sure everything will work. This is a pretty good idea if you are making radical changes or if you are unsure about your changes. 3.1.5 After installing the patchkit and recompiling the kernel with the option "WD8013", I am no longer able to reboot the machine. A cold boot (power on) runs fine, but after a reboot no boot drive is found by the BIOS. Besides having a 16-bit WD/SMC Ethernet card installed the machines try to boot using either a Adaptec 1742 or 1542 SCSI board to boot from. This answer was provided by Hellmuth Michaelis (hm@hcshh.hcs.de) and by Rodney Grimes (rgrimes@acacia). Remove "option WD8013" from the config files and recompile and reinstall the kernel. The reason that option WD8013 often causes this reboot problem is this: There is a requirement that all memory within a 128k bank in the 0xA0000 to 0xFFFFF region be either 16-bit or 8-bit. On a cold boot, the WD8013 boards are reset to 8-bit mode, the POST (Power On Self Test) passes without error. 386bsd comes up, the if_we.c driver places the WD8013 in 16-bit mode. Now on a soft boot when the BIOS runs some quick POST tests it finds a problem in the 0xA000 to 0xF000 region. You probably get a "beep-beep" when this happens. It means you have a memory size conflict. The machine has been mis-configured. This is a little known fact about 16-bit vs 8-bit option cards. It has caused more than one person to go crazy tracking down what they swear is a bug in the program. It is not, it is a flaw in the design of the ISA bus. The signal MEMCS16- must be returned the same for every 128k block of memory: B0000-CFFFF Must all be either 8-bit or 16-bit. D0000-FFFFF Must all be either 8-bit or 16-bit. In your particular configuration (WD8013 @ cc000) I suspect that you have another board in the B0000-CFFFFF region that is 8-bit, i.e. your Adaptec has an 8-bit BIOS on it! Try moving the board to the 0xD0000 region and see if it works there, you may still have a problem as many modern system BIOSes are now 8-bit. If your system BIOS is 8-bit, try shadowing the system BIOS region at 0xF0000 to 0xFFFFF, this effectively turns it into a 16-bit BIOS. Do not attempt to shadow the WD8013, it will cause you many headaches. As always, works for me, you mileage may vary.. 3.1.6 My system is complaining about stray interrupt 7. Is my machine going to explode or anything? No. They are caused by lots of things. They are, as far as anyone that should be expected to know about this stuff, harmless. There are ramifications on them being there, but for MOST users they do not pose a real threat to your operations. For those of you that are doing REALLY interrupt intensive stuff, you may want to grab a technical reference and figure out why the 8259 is not getting reset correctly. In spite of the number of times this has come up (and people have even referenced this section) there are still at least two questions on the net about this. A memorable one was a guy who was just vehement that the stray int 7 was what was keeping his system from booting. In fact, he went so far as to say that this document was practically worthless because I didn't tell him how to fix it. Of course, once he configured his hard drive controller so that it was on the right interrupt, his booting problem went away. I have said it before and I will say it again. For MOST users they do not pose a real threat to your operations. I have heard of three people (out of at least 2000) that have actually have problems so bad that they couldn't proceed. They bought new computers, and the problem went away. These stray interrupts are caused by something in the PC. I have yet to see a convincing explanation of precisely what, but they are definitely caused by something. There are four ways to deal with this problem. 1) Ignore them. They are spurious and do not effect the operation of your computer. 2) Implement the lpt driver. This way, the driver traps (the lpt driver expects IRQ 7) and then quietly discards them. That is why when folks implement the lpt driver the 'problem' goes away. The computer is taught how to ignore them. 3) Do what the original 386bsd code did. Comment out the diagnostic and associated code that tries to deal with them so you don't see the error message. 4) Buy a new computer that doesn't cause this problem. It is a known hardware problem with the 8259 being reset incorrectly in hardware. 3.1.7 I keep getting "wd0c: extra interrupt". What does it mean? It means that the drive was already processing a command (active) when it recieved an interrupt from the system telling it to see if it had anything to do. This is mostly harmless but could indicate that the drive/controller is having problems if the message appears often. 3.1.8 I found a bug in the kernel. How do I report it? Both NetBSD and FreeBSD include a facility called 'bugfiler'. While the instructions are included in both system, there is still some apparent confusion about when to use (and when to NOT use) bugfiler. Jordan K. Hubbard (jkh@whisker.lotus.ie) provides us with this short article for FreeBSD. To send bug reports, you want to use the sendbug(1) command. The entire package for sending and filing these bugs is known as "the bugfiler", which is where the confusion stepped in, but sendbug is definately the command you want to use. Second, it doesn't take a "net connection" to use sendbug, since all it does is package up your "bug report form" and mail it to us; no direct internet connectivity is required, just mail. So if you can send internet mail you can use sendbug, or you can also send mail to the `FreeBSD-bugs@freefall.cdrom.com' address (do NOT send it to FreeBSD.cdrom.com since it will BOUNCE, this is not the place to send bugs to, just to ftp stuff from!). NetBSD has a similar facility, but has a different program and host for bug reports. The program for NetBSD is called send-pr and is slightly different in several respects. It is recommended that NetBSD users see the man page on send-pr before filing bug reports. 3.1.9 Can someone please give a reasonably clear set of instructions as to how to get a "current" version of NetBSD running? Marc Wandschneider <marcwan@microsoft.com> provided this description of what he did to upgrade to the (then) current version of NetBSD: 1. Delete the old source tree, saving what I wanted to (a bunch of files moved around, and just unpacking the new one over the old will cause some problems) 2. Unpacked the new source tree. 3. ran the following sequence of commands: cd /usr/src/share/mk; make install cd /usr/src/include; make && make install setenv LDSTATIC -static setenv NOPIC cd /usr/src/lib/libc; make && make install cd /usr/src/gnu/lib/libmalloc; make && make install cd /usr/src/gnu/usr.bin/gas; make && make install cd /usr/src/gnu/usr.bin/ld; make && make install # You'll probably get some barfage from the above because # ld.so won't build yet. Ignore it and install ld anyway. cd /usr/src/gnu/usr.bin/gcc; make && make install unsetenv NOPIC LDSTATIC cd /usr/src/lib ; make && make install cd /usr/src/gnu/lib ; make && make install cd /usr/src/gnu/usr.bin/ld; make && make install cd /usr/src; make && make install At some point during the installation, your system will be fixed enough that many of these steps will no longer be required. For example, the new 'make' defines the variables OBJDIR and MACHINE_ARCH for you, so you will not need those once you get to that point. Until then, the following procedure may suit your needs better. #! /bin/csh unsetenv NOPIC LDSTATIC setenv MACHINE_ARCH i386 # Pick one of these three setenv lines. # setenv MAKE "make clean " # setenv MAKE "make obj " setenv MAKE cd /usr/src/share/mk make install cd /usr/src/include $MAKE make && make install setenv LDSTATIC -static setenv NOPIC cd /usr/src/usr.bin/make $MAKE make && make install cd /usr/src/usr.bin/rpcgen $MAKE make && make install cd /usr/src/lib/libc $MAKE make && make install cd /usr/src/gnu/lib/libmalloc $MAKE make && make install cd /usr/src/gnu/usr.bin/gas $MAKE make && make install cd /usr/src/gnu/usr.bin/ld $MAKE make && make install cd /usr/src/gnu/usr.bin/gcc2 $MAKE make && make install # unsetenv NOPIC LDSTATIC cd /usr/src/lib $MAKE make && make install cd /usr/src/gnu/lib $MAKE make && make install cd /usr/src/gnu/usr.bin/ld $MAKE make && make install cd /usr/src make && make install NOTE: At some point, you might very well come across an unresolved external __DYNAMIC in crt0.o. If this happens, edit the makefile for crt0.o (lib/csu/i386) and remove the -DDYNAMIC flag) make && make install. Then put the flag back in the makefile (but don't rebuild it until the natural order of things dicates that it happen) And Theo Deraadt provides this guidance when you get an error like "init_main.o: Undefined symbol _pdevinit referenced from text segment." You need to (1) install new config (2) make clean (3) re-config your kernel then this goes away 3.2 What exactly is this config file, anyway? What are all of these cryptic notations? I've annotated the distributed 386bsd GENERICISA file; my comments are delineated by the '--' symbols. THIS IS NOT A COOK-BOOK. YOU WILL NEED TO DO THE RESEARCH (LIKE LOOKING AT THE 20 OTHER CONFIG FILES) TO SEE WHAT IS CURRENT AND WHAT YOU WILL NEED IN YOUR CONFIG FILE. # # GENERICISA -- Generic ISA machine -- distribution floppy # -- BSD can be compiled for different hardware platforms, so it is important to -- define the hardware types. 386bsd can only be built for 386 or -- compatible machines, so this is sort of superfluous, but maintains -- compatibility with standard BSD config files. machine "i386" cpu "i386" -- The ident describes the machine for which this kernel is to be built. -- It is usually the system name -- "ROKKAKU", "REF", or whatever. -- This can be used for conditional compilation, so that kernel changes -- can be compiled in only for one machine. ident GENERICISA -- This should indicate the timezone of the system relative the -- Greenwich. 8 is PST; 4 is EST. A fuller explanation is provided -- below. timezone 8 dst 7 -- maxusers isn't strictly checked; it is just used to size several -- system data parameters. maxusers 10 -- The options control the conditional compilation of features into the -- kernel. The options can be listed all on a line separated by commas. -- They are #define'ed when the kernel is compiled, so that #ifdef's -- will work. An option can be given a value by appending an equals sign -- and a value (enclosed in double quotes) to the option name. -- Hopefully the names are at least somewhat self-explanatory. To -- discover what everything does, you'd have to go through the kernel -- looking for all of the appropriate #ifdef's. -- [Perhaps somebody else could list the *exact* meanings of these -- options and some of the other possible options?] options INET,ISOFS,NFS options "COMPAT_43" options "TCP_COMPAT_42" -- The config line controls the location of the root, swap, and dump -- devices. Anything not specified is defaulted. This is where you add -- support for multiple swap devices. Just list 'em, separated by 'and'. -- The config line below identifies the root drive as wd0 and the -- swap drives as wd0 and as0. See the section on swap devices in FAQ_02 -- for additional information. config "386bsd" root on wd0 swap on wd0 and as0 -- A 'controller' is a device or bus controller. 'isa' is obviously for -- the ISA bus. 'wd0' is for regular disk controllers, 'fd0' is for the -- floppies, and 'as0' is for SCSI disk controllers. controller isa0 -- The fields work as follows: -- a. What do you call this device? -- b. What controller is this on? As you can see, the disk controller -- talks to the ISA bus, and the disks talk to the disk controller. -- c. Where are the registers for the controller mapped into memory? -- This is #defined in /sys/i386/isa/isa.h. -- d. What IRQ is this device set up for? -- e. What routine should be called on an interrupt from the device? -- a b c d e -- vvv vvv vvvvvvv vv vvvvvv controller wd0 at isa? port "IO_WD1" bio irq 14 vector wdintr -- You need a 'disk' entry for every disk on the controller. In the -- config file originally shipped with 386bsd, both hard disks were -- incorrectly identified as wd0. Be sure to change the second occurrence -- to wd1, as I have done in below. disk wd0 at wd0 drive 0 disk wd1 at wd0 drive 1 controller fd0 at isa? port "IO_FD1" bio irq 6 drq 2 vector fdintr disk fd0 at fd0 drive 0 disk fd1 at fd0 drive 1 -- The 'drq' specifies the channel used for bus-mastering DMA. controller as0 at isa? port 0x330 bio irq 11 drq 5 vector asintr disk as0 at as0 drive 0 disk as1 at as0 drive 1 -- Define other physical devices. pc0 is the keyboard, npx0 drives the -- math coprocessor, and com* controls the com ports. device pc0 at isa? port "IO_KBD" tty irq 1 vector pcrint device npx0 at isa? port "IO_NPX" irq 13 vector npxintr device com1 at isa? port "IO_COM1" tty irq 4 vector comintr device com2 at isa? port "IO_COM2" tty irq 3 vector comintr -- Ethernet drivers of various sorts and the particular configuration -- information they require. For most installations, only one of these -- devices would normally be defined. device we0 at isa? port 0x280 net irq 2 iomem 0xd0000 iosiz 8192 vector weintr device ne0 at isa? port 0x300 net irq 2 vector neintr device ec0 at isa? port 0x250 net irq 2 iomem 0xd8000 iosiz 8192 vector ecintr device is0 at isa? port 0x280 net irq 10 drq 7 vector isintr -- Tape driver device wt0 at isa? port 0x300 bio irq 5 drq 1 vector wtintr -- The TCP/IP loop-back device, ethernet interface, slip interface, log -- device, and pseudo-terminals. pseudo-device loop pseudo-device ether pseudo-device sl 2 pseudo-device log pseudo-device pty 4 -- Devices required by VM. pseudo-device swappager pseudo-device vnodepager pseudo-device devpager Normally, there is an annotated configuration file called ALL which gives a list of all of the options for the configuration file. The configuration file that was used to create the list above was for a 386BSD system. Many things have changed in the config files for NetBSD and FreeBSD. As an example, the psuedo-devices swappager, vnodepager, and devpager are now full fledged devices. Like it said up at the top, use the config files that come with your system as a basis for your own experiments in kernel building. 3.2.1 Okay, fine. Why shouldn't I just add every device I can find to the kernel, so I'll never have to recompile this again? Because it takes up space. The kernel is wired into memory, so every byte it uses comes out of the pool of memory for everything else. It can't page out sections that aren't in use. If your kernel is larger than 640K, then it can't be loaded. You'll need to use Julian Elischer's bootblocks to put it in high memory, which seem to be fairly complex. Installing them (once they are compiled) is as easy as using disklabel. Newer versions of the *BSD kith provide the capability to build a kernel that is larger than 640K. Complete instructions are provided in the appropriate systems. 3.2.2 What should I remove from the kernel? What do you need? If you only have an SCSI controller, you don't need the wd0 device; if you have another kind of disk controller, you don't need as0. Unless you actually HAVE more than one Ethernet controller, you should comment out all but one of them. If you don't have an ethernet controller, you don't need any of the controllers or NFS compiled in. Without a CD-ROM, ISOFS is kind of pointless. Just look at what you have and think about what you really need. 3.2.3 I can't get enough remote login sessions or xterm sessions. I also can only get four seesions working at a time. What can I do? Increase the count of pseudo-terminals -- pseudo-device pty 12 # or whatever Every pseudo terminal should have a /dev/pty* entry. If you have 12 pseudo terminals, you should also have at least 12 pty devices in the /dev directory. The MAKEDEV script in /dev will create as many pseudo- terminals as you tell it to. 3.2.4 How do I get ddb, the kernel debugger, compiled into the kernel and running? Add the following line to the configuration file: pseudo-device ddb Build the kernel, then run dbsym on it: % dbsym ./386bsd Install it and go for it. Ctl-Alt-Esc drops you into the debugger. Note: DDB as shipped originally is a memory hog, and it is very difficult to get a kernel small enough with enough fun things in it to debug in 640K 3.2.5 Can I have more than one config file? Should I rename it to something else? Any other hints? You can create as many (or as few) config files as you desire. The system, once the patchkit is applied, will have between 10 and 15, each of which implements certain functions or features. In addition, the normal place for the patchkit to make changes to the config files is in the GENERICISA file. Since this file should remain unchanged and available, it is always a good idea to copy this file to a meaningful name and modify that file. In other words, change every reference in 3.1.1 from GENERICISA to HAL (or whatever you call your system). One final note. Every /sys/compile directory takes up 800K or so; you might want to watch to see how big these all get. 3.2.6 What is the meaning of the trap codes I get in panic messages? Sometimes this message appears in the form "trap type nn". That message means that the system received an unexpected (and unwanted) trap that probably indicates some form of kernel bug. These traps, are usually received from the kernel, in which case the trap.h definitions should be used. The number (which appears in place of "nn" above) is *NOT* the i386 or i386 trap type, it is a BSD-defined trap type number. The definitions of the various trap types can be found in /usr/include/machine/trap.h. two of the more common ones are: 9 T_PROTFLT protection fault (The kernel tried executing code which was not noted as "executable". This happens if the kernel jumps to a bogus location.) 12 T_PAGEFLT page fault (The kernel tried to access a bogus area of memory. This can happen if an invalid pointer is dereferenced.) This is a list of i386 trap codes (just to confuse the issue). Trap 0 Divide Error The DIV or IDIV instruction is executed with a zero denominator or the quotient is too large for the destination operand. Trap 1 Debug Exceptions Used in conjunction with DR6 and DR7, The following flags need to be tested to determine what caused the trap: BS=1 Single-step trap B0=1 AND (GE0=1 or LE0=1) Breakpoint, DR0, LEN0, R/W0 B1=1 AND (GE1=1 or LE1=1) Breakpoint, DR1, LEN1, R/W1 B2=1 AND (GE2=1 or LE2=1) Breakpoint, DR2, LEN2, R/W2 B3=1 AND (GE3=1 or LE3=1) Breakpoint, DR3, LEN3, R/W3 BD=1 Debug registers not available, in use by ICE-386 BT=1 Task Switch Trap 2 NMI Interrupt On PC/AT systems, the NMI input to the CPU is usually connected to the main memory parity circuit. By the time the error signal is generated, the data may have already been used in an instruction, so it isn't possible to reliably recover. And some not-so-common causes (from various sources): PS50+ : I/O channel check, system watch-dog timer time-out interrupt, DMA timer time-out interrupt parity errors on any 8-bit or 16-bit board pulling the IOCHCK* line low first generation of auto-switching EGA cards used NMI to trap port access for CGA emulation (e.g., ATI's EGA Wonder) Zeos Notebook low battery (perhaps other battery-based computers) Trap 3 Breakpoint The result of executing an INT 3 instruction. MS-DOS and Windows and some other non-386 systems use this for debugging. Code specific to the 386 and later processors should use the debugging features tied to Trap 1. Trap 4 INT0 Detected Overflow Occurs if an INT0 instruction is executed and the overflow flag (OF) is currently set. Trap 5 BOUND Range Exceeded Occurs if the BOUND instruction is executed and the array index points beyond the area of memory containing the array being tested. Trap 6 Invalid Opcode The value read at CS:IP is not a valid opcode. Trap 7 Coprocessor Not Available This occurs if the processor fetches an instruction that is for the coprocessor and no coprocessor is present. Trap 8 Double Exception (Fault) An exception occurred while trying to execute the handler for a prior exception. Example, an application causes a General Protection Fault (13) and the area of memory where the GPF handler should be is flagged not-present (paged-out?). The double-fault handler is invoked in these conditions. If a fault occurs while trying to run the double-fault handler, a triple-fault occurs and the CPU resets. The rules for deciding if a double-fault should occur or if the two faults can be handled serially are discussed in more detail in the Intel song book. Trap 9 Coprocessor Segment Overrun A page or segment violation occurred while transferring the middle part of a coprocessor operand to the NPX. Trap 10 Invalid Task State Segment During a task switch, the new TSS was invalid. Here is a table of conditions that Invalidate the TSS: TSS id + EXT The limit in the TSS descriptor is < 103 LTD id + EXT Invalid LDT selector or LDT not present SS id + EXT Stack segment selector is outside table limit SS id + EXT Stack segment is not a writable segment SS id + EXT Stack segment DPL does not match new CPL SS id + EXT Stack segment selector RPL <> CPL CS id + EXT Code segment is outside table limit CS id + EXT Code segment selector does not refer to code segment CS id + EXT DPL of non-conforming code segment <> new CPL CS id + EXT CPL of conforming code segment > new CPL DS/ES/FS/GS id + EXT DS, ES, FS or GS segment selector is outside table limits DS/ES/FS/FS id + EXT DS, ES, FS, or GS is not readable segment Trap 11 Segment Not Present Occurs when the "present" bit of a descriptor is zero. This can occur while loading any of these segment registers CS, DS, ES, FS, or GS. Loading SS causes a Stack fault. Also occurs when attempting to use a gate descriptor that is marked "not present", and if attempting to load the LDT with an LLDT instruction. Note that loading the LDT during a task switch causes an "invalid TSS" trap. Trap 12 Stack Fault A limit violation relating to an address referenced off the SS register. Includes POP, PUSH, ENTER and LEAVE opcodes, as well as references such as MOV AX,[BP+8] (which has an implied SS:). Also causes by loading SS with a descriptor that is marked "not present". Trap 13 General Protection Fault (GPF) Americas Favorite, in the Windows 3.0 world, it is known as the UAE error. The instruction tried to access data out of the bounds designated by the descriptors. The access that failed can be a read, write or instruction fetch. There are 15 classifications of GPFs: 1. Exceeding segment limit when using CS, DE, ES, FS or GS. 2. Exceeding segment limit when referencing a descriptor table. 3. Transferring control to a segment that is not executable. 4. Writing into a read-only data segment or into a code segment. 5. Reading from an execute-only segment. 6. Loading the SS register with a read-only descriptor (unless the selector comes from the TSS during a task switch, in which case a TSS exception occurs.) 7. Loading SS, DS, ES, FS or GS with the descriptor of a system segment. 8. Loading, DS, ES, FS or GS with the descriptor of an executable segment that is not also readable. 9. Loading SS with the descriptor of an executable segment. 10. Accessing memory via, DS, ES, FS or GS when the segment register contains a null selector. 11. Switching to a busy task. 12. Violating privilege rules. 13. Loading CR0 with a PG=1 and PE=0. 14. Interrupt or exception via trap or interrupt gate from V86 mode to privilege level other than zero. 15. Exceeding the instruction limit of 15 bytes (this can only occur if redundant prefixes are placed before an instruction). To determine which condition caused the trap, you need the instruction, the contents of all associated registers, particularly the segment registers involved, then the various LDT, GDT and page control tables. Lots of common coding errors cause the GPFs. Even a stack imbalance will usually show up as a GPF. Even MOV AX,7 MOV ES,AX or MOV AX,5 PUSH AX POP DS will get a GPF error. You can't use a segment register for "temporary storage" of any old value the way you could on the 8086. The values loaded into the segment registers are checked in protected mode. Trap 14 Page Fault The page directory or page table entry needed for the address translation has a zero in the present bit, or the current procedure does not have sufficient privilege to access the indicated page. Trap 15 (reserved) Trap 16 Coprocessor Error The coprocessor asserted the ERROR# input pin on the 386 (internal on the 486) Trap 17 Alignment Check (486 and later) If enabled, this trap will occur if a data fetch does not occur on a word boundary. I don't know of any software that activates this feature yet. I have seen SCO UNIX get this error on early Cyrix processors, even though SCO had not enabled the feature. Trap 18-32 (reserved) [answered by Frank Durda IV <uhclem@nemesis.lonestar.org> and jim mullens jcm@ornl.gov -or- mullens@jamsun.ic.ornl.gov] ------------------------------------------------------------------------------- 3.2.7 I have been getting a lot of "virtual memory exhausted" errors when I am compiling a program with a really big static array. I have 128Meg of memory and 8Gig of swap. How can this be happening? If you are using Csh, you can simply unlimit your processes in your system level /etc/csh.cshrc file or your personal .cshrc file. You can also modify your kernel so that the amount of memory available is less limiting. J"org Wunsch (j@tcd-dresden.de) provides us with this brief description: From a recent posting i just made, regarding the problem how much virtual memory one could get. | On the other hand, i've also changed the definitions you | mentioned. But i didn't like to modify the header files, and | actually, modifying the values is as easy as: | | options "DFLDSIZ='(16 * 1024 * 1024)'" | options "MAXDSIZ='(64 * 1024 * 1024)'" | | Include the above lines into your kernel's config file, reconfig | and rebuild it. | This is just a hint for those people poking around with compiling large source files. Especially, due to some gcc problems with large static arrays, compiling X applications with huge bitmaps would cause virtual memory trouble. Increasing the limits (o'course, as long as the h/w resources suffice) could help there. The default definitions for the above parameters are found in /usr/include/machine/vmparam.h. 3.2.8 Where can I learn more about all this? We've skipped over a lot of details here; the straight dope comes from "Building Berkeley UNIX Kernels with Config", by Samuel J. Leffler and Michael J. Karels. 3.2.9 Does anyone have a system building script that takes things like building a new config and multiple config files into account? This is the program that I use to rebuild my kernel. See the note in the file about my 'test' program. You may elect to build a new config every time, or not, depending on your requirements. #! /bin/sh # # Script to rebuild the kernel. # if [ `whoami` != 'root' ] ; then echo 'You must be root to successfully proceed from this point' exit 1 fi # # Set up the environment # if [ X$MACHINE_ARCH = "X" ] ; then MACHINE_ARCH=i386 fi if [ -f /netbsd ] ; then ARCHDIR='/arch' fi # # Rebuild Config # # I am using a modified test(1) that allows for file date comparisons. # You can either get my patches (if they aren't already included), # modify test() yourself, or get the GNU ShellUtils test(1) program. # if [ /usr/src/usr.sbin/config -ot /usr/sbin/config ] ; then echo "Config Up To Date" else cd /usr/src/usr.sbin/config make clean make depend make make install fi cd /sys make make install # # Modify the local Configuration File # echo `tput clr` cd /sys$ARCHDIR/i386/conf if [ "X$CONFIG_NAME" = "X" ]; then CONFIG_NAME=GENERIC fi if [ "X$1" = "X" ]; then echo "Configuration Files available:" ls [A-Z]* echo " " echo -n "Enter the name of the config file to use: " read CONFIG_NAME echo else CONFIG_NAME=$1 fi if [ ! -f $CONFIG_NAME ]; then cp GENERIC $CONFIG_NAME fi echo "Modifying $CONFIG_NAME config file" echo -n "Press return to continue (q to quit) " read ans ans=`echo $ans | cut -c1 | tr 'QqYy' 'qqqq'` if [ "X$ans" = "Xq" ] ; then exit 0 fi vi $CONFIG_NAME #config.new $CONFIG_NAME config $CONFIG_NAME COMPILE_DIR=/sys$ARCHDIR/i386/compile/$CONFIG_NAME cd $COMPILE_DIR make depend make if [ $? -ge 1 ] ; then echo "Errors encountered" else if [ -f netbsd ] ; then PROGNAME=netbsd else if [ -f freebsd ] ; then PROGNAME=freebsd else PROGNAME=386bsd fi fi echo `tput clr` echo "" echo " Manual Installation is recommended. The following files should be" echo "copied/linked/moved to the root directory. The following steps are" echo "suggested:" echo "" echo " mv /$PROGNAME /$PROGNAME.old" echo " mv $COMPILE_DIR/$PROGNAME /$PROGNAME" echo " reboot" echo "" echo "Remember that the new kernel changes will not take place until you " echo "re-boot the system." fi 3.3 X11/XFree86/XS3 3.3.1 What options should I define to get the X extensions included? Once you have applied the patch kit, the only thing left to do is to modify the config file to include the following line: options XSERVER, UCONSOLE recompile the kernel and the kernel should support X. 3.3.2 Where can I get the FAQ for 'X'? Steve Kotsopoulos' general 'X on Intel-based Unix' FAQ available by anonymous ftp from export.lcs.mit.edu in /contrib/Intel-Unix-X-faq. 3.3.3 Why does X drop characters when using xdm? When I run xdm from the console, it keeps losing keystrokes and the shift keys don't always work. Why? You need to run xdm with the -nodaemon flag. The reason is xdm normally detaches from the keyboard. This allows other processes (like getty) to return to reading from the keyboard. A race condition results, where some keystrokes are sent to xdm and others are sent to other processes. Using the -nodaemon flag causes xdm to stay attached to the keyboard so no other process can use it. This answer comes from Michael C. Newell (root@wanderer.nsi.nasa.gov) This bit of trivia is also covered in detail in the X FAQ and the README that accompanies XFree86. 3.4 Compiler and Library routines There are several questions that could probably be included here. See also Section 4 for some of the more common 'missing modules' that also happen to be library routines. 3.4.1 Which C compiler is shipped with my 386BSD derived system? The standard compiler released with 386bsd 0.1 is GCC 1.38. This version is considered by many people to be the most stable of the GCC versions. All other Net/2 derived BSD systems have both 1.38 and 2.4+ available. NetBSD 0.9, for example, is completely compilable using GCC 2.4.5, which is included as the default compiler. FreeBSD also ships with the same compiler. 3.4.2 Where is libcompat.a? The library libcompat.a is (working from memory here) completely deprecated in 386bsd. The only exceptions might be the re_comp and re_exec routines, which are discussed in detail in section 4. In addition, things will be added to libcompat.a as they are deprecated in the newer versions of NetBSD and FreeBSD. The getreuid() and setreuid() stuff may be heading that way (if they aren't there already. The easiest way around not having a libcompat.a is to simply link it to a small library, since virtually every other function that is expected in libcompat.a is already include libc.a. 3.5 You promised to talk about timezones below. Are you going to? >I've seen lots of stuff about timezone's being a bit dodgy, >especially with most European timezones changing over to DST on >the 27th March. I must say that that was NOT the case for me - >pumpy (the author's system) is running off the >/usr/share/zoneinfo/GB-Eire timezone file, (symbolically) linked >to /etc/localtime, the CMOS clock is running off GMT, and the >kernel is compiled with "timezone 0". I use /usr/share/zoneinfo/MET as /etc/localtime and have the kernel configured as timezone -1 dst 4 (My wife is running DOS on this machine for doom sometimes ;-) I set this strange dst value after diging in some old ultrix(?) man pages. There were several dst-changing-method listed and 4 was the code for the central europe one. This gave me an idea... I use an Ultrix box every day, so why not... Now, I don't know how closely this applies to NetBSD since Ultrix is based on a much older version of BSD, and this isn't for the kernel config, but for an envar of timezone values, but it's at least somewhat enlightening on possible meanings for these things. Could someone in the know shed light on how accurately this models the timezone stuff in the kernel config? When I did "man timezone" this is what I got (portion of this quoted from the DEC MIPS Ultrix 4.3a timezone(3) manpage, slightly hacked by me (Michael L. VanLoon (michaelv@iastate.edu)) STD offset [DST [offset][,start[/time],end[/time]]] the components of the string have the following meaning: STD and DST Three or more characters that are the designation for the standard (STD) or summer (DST) time zone. Only STD is required; if DST is missing, then summer time does not apply in this locale. Upper- and lowercase letters are explicitly allowed. Any characters except a leading colon (:), digits, comma (,), minus (-), plus (+), and ASCII NUL are allowed. offset Indicates the value to be added to the local time to arrive at Coordinated Universal Time. The offset has the form: hh[:mm[:ss]] The minutes (mm) and seconds (ss) are optional. The hour (hh) is required and may be a single digit. The offset following STD is required. If no offset follows DST, summer time is assumed to be one hour ahead of standard time. One or more digits may be used; the value is always interpreted as a decimal number. The hour must be between 0 and 24, and the minutes (and seconds) - if present - between zero and 59. If preceded by a "-", the time zone is east of the Prime Meridian; otherwise it is west (which may be indicated by an optional preceding "+"). start and end Indicates when to change to and back from summer time. Start describes the date when the change from standard to summer time occurs and end describes the date when the change back happens. The format of start and end must be one of the following: Jn The Julian day n (1 < n < 365). Leap days are not counted. That is, in all years, including leap years, February 28 is day 59 and March 1 is day 60. It is impossible to explicitly refer to the occasional February 29. n The zero-based Julian day (0 < n < 365). Leap days are counted, and it is possible to refer to February 29. Mm.n.d The nth d day of month m (1 < n < 5, 0 < d < 6, 1 < m < 12). When n is 5 it refers to the last d day of month m. Day 0 is Sunday. time The time field describes the time when, in current time, the change to or from summer time occurs. Time has the same format as offset except that no leading sign (a minus (-) or a plus (+) sign) is allowed. The default, if time is not given, is 02:00:00. As an example of the previous format, if the TZ environment variable had the value EST5EDT4,M4.1.0,M10.5.0 it would describe the rule, which went into effect in 1987, for the Eastern time zone in the USA. Specifically, EST would be the designation for standard time, which is 5 hours behind GMT. EDT would be the designation for DST, which is 4 hours behind GMT. DST starts on the first Sunday in April and ends on the last Sunday in October. In both cases, since the time was not specified, the change to and from DST would occur at the default time of 2:00 AM. The timezone call remains for compatibility reasons only; it is impossible to reliably map timezone's arguments (zone, a `minutes west of GMT' value and DST, a `daylight saving time in effect' flag) to a time zone abbreviation. 3.5.1 How do you change the timezone on NetBSD (FreeBSD also?)? Relink /etc/localtime. This will correct the difference from GMT (or its trendy equivelant) to your local timezone. In addition, the kernel needs to be modified to take the clock time in your CMOS into account. Since most folks that run DOS prefer to have their clocks set to local time, the timezone hack was introduced to allow the kernel to adjust the CMOS clock time to GMT. Once GMT has been computed, the /etc/localtime file can be referenced to determine the corrected local time. All generic kernels are built using the offset from California (why is anyone's guess:-) so just about everyone's clock will be off by their timezone offset from Berkeley. 3.5.2 The translation between seconds-since-the-epoch and date differs by about 18 seconds between BSD and other Unixes when running ntp; why? See ntp FAQ. Apparently, the time correction takes leap seconds into account twice. The timezone files in our system take the leap seconds into account in the kernel, and nntp takes the same 18 leap seconds into account when syncing the time. Because of that, the time will appear to be off by eighteen seconds. (Henning Schulzrinne) -- TSgt Dave Burgess | Dave Burgess NCOIC, USSTRATCOM/J6844 | *BSD FAQ Maintainer Offutt AFB, NE | Burgess@cynjut.infonet.net or ...@s069.infonet...