From mboxrd@z Thu Jan 1 00:00:00 1970 From: Weidong Han Subject: Re: Re: [PATCH][RFC] gfx_passthru: warning when vgabios rom has invalid checksum Date: Mon, 22 Feb 2010 18:08:41 +0800 Message-ID: <4B8257A9.8080600@intel.com> References: <4B8219F1.5040301@jp.fujitsu.com> <4B823088.8090706@intel.com> <4B82398B.6020109@jp.fujitsu.com> <4B8246C5.4090005@intel.com> <4B8252A5.4020008@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4B8252A5.4020008@jp.fujitsu.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Noboru Iwamatsu Cc: "xen-devel@lists.xensource.com" , "Ian.Jackson@eu.citrix.com" List-Id: xen-devel@lists.xenproject.org Noboru Iwamatsu wrote: > Hi Weidong, > > > How did you recalculate it? is it possible to recalculate it when detect > > invalid checksum? > > Checking and recalculating the VGABIOS checksum is being processed > in setup_vga_pt() in hw/pass-through.c. > I thought you have written that part. > > If the checksum is invalid, current setup_vga_pt() always overwrites > it with the recalculated value. > > What I mention is: the VGABIOS checksum must have been already > recalculated by system BIOS. So, when setup_vga_pt() detects the > invalid one, something might be wrong. > > But, I'm not sure all BIOS should work as described in PCIFW Spec. > Actually, my Q35 had invalid checksum. > Now I understand. Because your Q35 works with recalculated checksum, I prefer to only add a warning message, and continue to load rom for gfx passthru. Regards, Weidong > > I attach another patch: > This stops loading vgabios if the checksum is wrong. > > Signed-off-by: Noboru Iwamatsu > > >> Noboru Iwamatsu wrote: >> >>> Hi, >>> >>> >>>>> Intel DX58SO + GeForce GTS250: checksum is OK. >>>>> Intel DX58SO + GeForce 9600GT: checksum is OK. >>>>> Fujitsu Q35 M/B + IGD: checksum is bad. >>>>> >>>>> >>>> What does "checksum is bad" mean here? >>>> >>> It means shadowed VGABIOS has invalid checksum >>> and requires recalculating. >>> >>> >>>>> What do you think, Weidong? >>>>> Is just warning enough? Or, should we stop loading the rom? >>>>> >>>>> >>>>> >>>> Does it still work or not when checksum is bad? If it works, we should >>>> not stop loading the rom. >>>> >>> When the checksum is bad, >>> if it is not recalculated, guest has some trouble about handling the >>> VGA (unable to show BIOS screen, unable to load the gfx driver >>> properly, ...). >>> >> For this case, it's reasonable to warning and stop loading rom. We >> didn't encounter this issue. >> >>> If it is recalculated, it seems to work fine. >>> >> How did you recalculate it? is it possible to recalculate it when detect >> invalid checksum? >> >> Regards, >> Weidong >> >> >>> Regards, >>> Noboru. >>> >>> >>>> Noboru Iwamatsu wrote: >>>> >>>>> Hi, >>>>> >>>>> According to the "PCI Firmware Spec Rev 3.0", >>>>> the system firmware have to write the new checksum after resizing >>>>> the expansion ROM area. >>>>> >>>>> So, when re-using the shadowed VGABIOS, the checksum must >>>>> be valid, and if it is invalid, we should consider the BIOS has >>>>> a bug or memory area is corrupted. >>>>> >>>>> This patch just add the warning message when checksum requires >>>>> recalculation. >>>>> >>>>> I tried this following environments. >>>>> >>>>> Intel DX58SO + GeForce GTS250: checksum is OK. >>>>> Intel DX58SO + GeForce 9600GT: checksum is OK. >>>>> Fujitsu Q35 M/B + IGD: checksum is bad. >>>>> >>>>> >>>> What does "checksum is bad" mean here? >>>> >>>>> What do you think, Weidong? >>>>> Is just warning enough? Or, should we stop loading the rom? >>>>> >>>>> >>>>> >>>> Does it still work or not when checksum is bad? If it works, we should >>>> not stop loading the rom. >>>> >>>> Regards, >>>> Weidong >>>> >>>>> Regards, >>>>> Noboru. >>>>> >>>>> >>> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@lists.xensource.com >> http://lists.xensource.com/xen-devel >> > >