Messages in this thread | | | Date | Thu, 16 Dec 2010 08:28:33 -0800 | From | "H. Peter Anvin" <> | Subject | Re: kdump broken on 2.6.37-rc4 |
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On 12/16/2010 06:39 AM, Vivek Goyal wrote: > On Wed, Dec 15, 2010 at 08:29:01PM -0800, Yinghai Lu wrote: >> please check >> >> [PATCH] x86, crashkernel, 32bit: only try to get range under 512M >> >> Steanishlaw report kdump is 32bit is broken. >> >> in misc.c for decompresser, it will do sanity checking to make sure heap >> heap under 512M. > > Thanks Yinghai. I am wondering why on 32bit heap has to be with-in 512MB. > I think you are referring to following check in > arch/x86/boot/compressed/misc.c. > > if (end > ((-__PAGE_OFFSET-(512 <<20)-1) & 0x7fffffff)) > error("Destination address too large"); > > It was introduced here. > > commit 968de4f02621db35b8ae5239c8cfc6664fb872d8 > Author: Eric W. Biederman <ebiederm@xmission.com> > Date: Thu Dec 7 02:14:04 2006 +0100 > > [PATCH] i386: Relocatable kernel support > > Eric, > > It has been long. By any chance would you remember where does above > constraint come from? >
It might, in fact, be bogus; specifically a proxy for the fact that we need the kernel memory including bss and brk below the lowmem boundary, which isn't well-defined.
-hpa
-- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
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