Messages in this thread | | | Date | Fri, 22 Jun 2007 21:33:27 +0100 | From | Alan Cox <> | Subject | Re: [PATCH] x86-64: disable the GART before allocate aperture |
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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 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).
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