Messages in this thread | | | Date | Fri, 17 Dec 2010 10:21:24 -0800 | From | Yinghai Lu <> | Subject | Re: kdump broken on 2.6.37-rc4 |
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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.
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...
Thanks
Yinghai
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