Re: [Qemu-devel] [PATCH 0/6] AHCI Device Fixes

[Paolo Bonzini]

>> Yeah, I was wondering if any commands could have <512 bytes response...
>>   I sort of convinced myself that the answer was no for ATA commands, but
>> stupidly forgot about packet (SCSI) commands.  Their results are
>> obviously shorter than 512 bytes.
> 
> Are you referencing the sglist underflow patch? (#5 instead of #3)

Hmm, yeah.

> There were cases in the code already where we /assumed/ that having any bytes
> implied we had at least a sector's worth.

Even for ATAPI?

 If there are valid cases for
> the sglist to have less than a sector's worth (SCSI) then I'll need to
> touch that again as well and update all the assumptions in the IDE code
> to look for numbytes instead of numsectors.

cmd_inquiry can return 36 bytes.  That can be both PIO and DMA.  SeaBIOS
only uses the DMA variant for AHCI.

Paolo