Re: [PATCH] ata.mod under qemu

[Christian Franke]

Pavel Roskin wrote:
> On Mon, 2009-05-18 at 19:36 -0400, Pavel Roskin wrote:
> 
> > I did a quick check, and your patch has no effect on my system.  I'm
> > using Fedora 11 with qemu 0.10.  After inserting the ata module, ls
> > shows no disks, with or without your patch.
> > 
> 
> Never mind, my "quick check" was too quick.  I forgot to change
> prefix, so it's just ls that was failing.
> 
> Your patch makes the CD-ROM visible.  Without your patch, only hard
> drivers are seen.
> 

Thanks for the problem report.

According to 'qemu-0.10.4/hw/ide.c', the (READY bit of the) status
register is actually cleared by some commands like RESET and DIAGNOSE if
an ATAPI device is connected. This conforms to ATA parallel transport
standard.

When I added the '(sts == 0x00)' check, I made the false assumption that
device detection through the READY bit is safe. It was added to speed-up
the detection of the missing slave port of some SATA controllers working
in IDE-mode. The check can be safely removed, the only drawback is an
extra ~1s timeout for each SATA controller.

I will commit a fix soon.

-- 
Regards,
Christian Franke