Software Not Affected

Software Not Affected

As a result of hardware design and software fixes, none of the following kinds of software are affected by the problem:

Code using PIO to manage a device.
The IO4 problem cannot be triggered by PIO, either at the user or kernel level.
User-level code using the udmalib library or the dslib SCSI library.
These libraries for user-level DMA contain the fix, or use kernel functions that are fixed.
User-level code based on user-level interrupts (ULI) or external interrupts.
These facilities are not relevant to the IO4 problem.

Among kernel-level drivers, only drivers that directly program DMA can be affected. STREAMS drivers are not affected; nor are pseudo-device drivers; nor are drivers that use only PIO and memory mapping. Drivers that are not used on Challenge-architecture machines are not affected; for example an EISA-bus driver cannot be affected.

SCSI drivers that use the host adapter interface (see "Host Adapter Facilities") are also not affected. Silicon Graphics host adapter drivers contain the fix. Host adapter drivers from third parties may need to be fixed, but this does not affect drivers that rely on the host adapter interface.

Drivers that do only block-mode I/O for the filesystem, and do not implement a character I/O interface (or do not support the character I/O interface using DMA) are not affected. This is because the filesystem always requests I/O in cache-line-sized multiples to buffers that are cache-aligned.