Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [PATCH] x86-64: disable the GART before allocate aperture | Date | Fri, 22 Jun 2007 23:28:20 +0200 |
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On Friday 22 June 2007 22:33, Alan Cox wrote: > On Fri, 22 Jun 2007 12:31:24 -0700 > > Muli Ben-Yehuda <muli@il.ibm.com> wrote: > > On Fri, Jun 22, 2007 at 12:19:15PM -0700, Yinghai Lu wrote: > > > [PATCH] x86-64: disable the GART before allocate aperture > > > > > > For K8 system: 4G RAM with memory hole remapping enabled, or more > > > than 4G RAM installed. when mem is allocated for GART, it will do > > > the memset for clear. and for kexec case, the first kernel already > > > enable that, the memset in second kernel will cause the system > > > restart. So disable that at first before we try to allocate mem for > > > it. > > > > Why does the memset in the second kernel cause a system restart? > > You've got mapped live gart pages from the previous kernel. Even if you > disable the gart before a memset
It's probably too late then. It could also interfere with other operations. If anything the GART should be disabled during kexec shutdown. Perhaps we just need a suitable suspend function that does that. Eric, any preferences?
> you may well have the video card using > gart translations and possibly live IOMMU mappings for devices using it > via bus mastering - and those will cause you MCE exceptions with a > corrupt cpu context flag (ie not nicely recoverable).
We disable those machine checks on K8 because they're not fully reliable.
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