Re: PATA Sil680 Disabling IRQ

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

> For most of unsupported commands, it will be aborted by drive.
> However, for some unsupported commands, it may not.  I suspect these
> bad commands are the new ones in ATA8 issued to some drives with old
> firmware. For instance, can you try command 0x5E (Trusted Send PIO
> data out) with sector count set to 1 and see what happens?

Well the kernel as of 2.6.24 defaults to blocking treacherous computing
commands 8)

> The blame is probably on drives which should have aborted these
> commands. But the reality is that libata will handle variety of drives
> including the ones with old firmware.  So the question here is whether
> libata PATA code can be more fault tolerate. It seems the weakest link
> is on PATA PIO since I have not been able to reproduce the IRQ
> disabling problem on DMA operations.

If you send crap to a drive you will get junk as a result. Only the
superuser can do this so that behaviour is fine. The superuser can also
crash the machine a million other ways. End users cannot send arbitary
commands to the drive.

Ditto they may know that an "unsupported" command for their ATA version
is actually a vendor private command for the specific drive they have.

Alan