Messages in this thread | | | Subject | Re: [PATCH] disable CPU side GART accesses | From | Bob Montgomery <> | Date | Thu, 16 Oct 2008 13:26:48 -0600 |
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On Thu, 2008-10-16 at 17:43 +0000, Yinghai Lu wrote: > On Thu, Oct 16, 2008 at 10:00 AM, Bob Montgomery <bob.montgomery@hp.com> wrote: > > > > The problem occurs when the copy operation reads from the GART aperture > > (iommu window) and wakes up the GART translation hardware. This patch > > stops that by telling the GART to ignore addresses that come from the > > CPU and to only translate addresses from the IO side. > > why kdump need to copy those area? those area is supposed to be > reserved in e820 table by BIOS or first kernel. > > YH
The crashdump analysis tools do not need a copy of this area. But if a user tool associated with the kdump operation manages to touch it through /proc/vmcore or /dev/oldmem, it can crash the kdump kernel. This seemed like a simple and logical way to prevent that danger.
Bob Montgomery
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