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    SubjectRe: kdump broken on 2.6.37-rc4
    On Fri, Dec 17, 2010 at 10:21:24AM -0800, Yinghai Lu wrote:
    > On 12/17/2010 10:02 AM, Vivek Goyal wrote:
    > > On Fri, Dec 17, 2010 at 09:56:42AM -0800, H. Peter Anvin wrote:
    > >> On 12/17/2010 09:01 AM, Vivek Goyal wrote:
    > >>> On Thu, Dec 16, 2010 at 07:58:48PM -0800, Yinghai wrote:
    > >>>> Please don't do that to 64 bit
    > >>>>
    > >>>> My big system with 1024g memory and a lot of cards with rhel 6 to make kdump work must have crashkernel=512m and second kernel need to take pci=nomsi
    > >>>>
    > >>>
    > >>> I agree here that we should not do it for 64 bit.
    > >>>
    > >>> - Just because we need it for 32 bit does not mean we should limit it for
    > >>> 64bit. And we do want to have the capability to boot the kernel from as
    > >>> high memory as possible so creating another aritificial limit is counter
    > >>> to that.
    > >>>
    > >>> - I would not worry too much about backward compatibility and allow
    > >>> booting 32bit kernel till 768MB. The reason being that most of the
    > >>> distros use same kernel for crash dumping as regular kernel. Maintainig
    > >>> two separate kernels is big hassle.
    > >>>
    > >>> So a small set of people who run into issue, would need to change kernel
    > >>> command line "crashkernel=128M@64M" or something similar.
    > >>>
    > >>
    > >> Do we have actual testing for how high the 64-bit kernel will load?
    > >
    > > I will do some experiments on my box today and let you know.
    > if bzImage is used, it is 896M.

    Strangely on my x86_84 systems with 37-rc6, I am trying to reserve memory and
    nothing shows up on /proc/iomem. dmesg says that I am reaserving 128M at 64M
    but nothing in /proc/iomeme. Going back to .36 kernel and see what

    Ok, last time we had looked that kexec-tools had constraint to load
    bzImage and initrd below 896MB and it must be coming from that.

    > or crashkernel=... will take two ranges like one high and one low.
    > also kexec bzImage in 64bit should use startup_64 aka 0x200 offset instead of startup_32 in arch/x86/boot/compressed/head_64.S
    > then bzImage can be put above 4G...

    Neil had been trying that but AFAIK, he had no success. I don't know but
    he was struggling with setting up pages tables in kexec for 64bit startup.

    But yes, making use of 64bit entry point is in the wish list.


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      Last update: 2010-12-17 19:37    [W:0.022 / U:10.032 seconds]
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