[pve-devel] Fwd: [Qemu-devel] [PATCH] ahci: properly reset PxCMD on HBA reset

Alexandre DERUMIER aderumier at odiso.com
Fri Aug 31 14:02:22 CEST 2012


maybe this is the problem with win7 ?


----- Mail transféré ----- 

De: "Jason Baron" <jbaron at redhat.com> 
À: "Alexander Graf" <agraf at suse.de> 
Cc: kwolf at redhat.com, aliguori at us.ibm.com, mst at redhat.com, "jan kiszka" <jan.kiszka at siemens.com>, qemu-devel at nongnu.org, armbru at redhat.com, yamahata at valinux.co.jp, "alex williamson" <alex.williamson at redhat.com>, pbonzini at redhat.com, lcapitulino at redhat.com, afaerber at suse.de 
Envoyé: Jeudi 30 Août 2012 21:59:42 
Objet: Re: [Qemu-devel] [PATCH] ahci: properly reset PxCMD on HBA reset 

On Fri, Aug 24, 2012 at 06:39:02AM +0200, Alexander Graf wrote: 
> > While testing q35, I found that windows 7 (specifically, windows 7 ultimate 
> > with sp1 x64), wouldn't install because it can't find the cdrom or disk drive. 
> > The failure message is: 'A required cd/dvd device driver is missing. If you 
> > have a driver floppy disk, CD, DVD, or USB flash drive, please insert it now.' 
> > This can also be reproduced on piix by adding an ahci controller, and 
> > observing that windows 7 does not see any devices behind it. 
> > 
> > The problem is that when windows issues a HBA reset, qemu does not reset the 
> > individual ports' PxCMD register. Windows 7 then reads back the PxCMD register 
> > and presumably assumes that the ahci controller has already been initialized. 
> > Windows then never sets up the PxIE register to enable interrupts, and thus it 
> > never gets irqs back when it sends ata device inquiry commands. 
> > 
> > I believe this change brings qemu into ahci 1.3 specification compliance. 
> > 
> > Section 10.4.3 HBA Reset: 
> > 
> > " 
> > When GHC.HR is set to '1', GHC.AE, GHC.IE, the IS register, and all port 
> > register fields (except PxFB/PxFBU/PxCLB/PxCLBU) that are not HwInit in the 
> > HBA's register memory space are reset. 
> > " 
> > 
> > I've also re-tested Fedora 16 and 17 to verify that they continue to work with 
> > this change. 
> 
> What a nasty little bug. If it makes it work for you, the change is all fine from my POV (and should go into 1.2). 
> 

Ok, I don't see it 1.2.0-rc2. If others are ok with this for 1.2, whose 
tree should this go through? 

Thanks, 

-Jason 




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