Re: REGRESSION: 8fc5b4d: Unable to compile x86_64 kernel with x86_32 userland

["H. Peter Anvin" <hpa@zytor.com>]

It says "32-bit mode" which means it is another issue: we are dropping -m64 at some point.

On August 20, 2014 7:56:30 AM CDT, Vivek Goyal <vgoyal@redhat.com> wrote:
>On Wed, Aug 20, 2014 at 08:24:08AM +0200, Thomas Glanzmann wrote:
>> Hello Vivek,
>> commit 8fc5b4d introduces a regression that no longer allows to
>compile
>> x86_64 kernel under x86_32 userland. TJ on freenode/#kernel did
>analyze
>> it:
>> 
>> > (mini) [~/work/linux-2.6] make
>> > scripts/kconfig/conf --silentoldconfig Kconfig
>> >   CHK     include/config/kernel.release
>> >   UPD     include/config/kernel.release
>> >   CHK     include/generated/uapi/linux/version.h
>> >   CHK     include/generated/utsrelease.h
>> >   UPD     include/generated/utsrelease.h
>> >   CC      arch/x86/purgatory/purgatory.o
>> > arch/x86/purgatory/purgatory.c:1:0: error: code model 'large' not
>supported in the 32 bit mode
>> > make[1]: *** [arch/x86/purgatory/purgatory.o] Error 1
>> > make: *** [archprepare] Error 2
>> 
>> 08:10 < TJ-> Glanzmann: The purgatory code from kexec is specifying
>".code64"
>> 08:11 < TJ-> Glanzmann: so when your local 32-bit linker tries to
>deal with that ... it errors
>> 08:14 < TJ-> Glanzmann: there's only one introducing the purgatory
>stuff
>> 08:14 < TJ-> 8fc5b4d Fri Aug 8 15:57:32 2014 -0700 Vivek Goyal
>purgatory: core purgatory functionality
>
>Hi Thomas,
>
>Thanks for the report. I think this is also happening because purgatory
>is
>right now being compiled with compiler option -mcmodel=large. There was
>another report where older version of gcc did not support
>-mcmodel=large.
>
>A patch is sitting in akpm's tree. That patch puts the new code under
>a new config option CONFIG_KEXEC_FILE. So as long as you don't enable
>CONFIG_KEXEC_FILE=y, you should be fine. This should not impact any of
>the existing functionality. Just that you will not get the benefit of
>new system call.
>
>http://ozlabs.org/~akpm/mmotm/broken-out/kexec-create-a-new-config-option-config_kexec_file-for-new-syscall.patch
>
>I hope this patch gets merged soon.
>
>In the mean time I am trying to figure out how can I move away from
>using -mcmodel=large for purgatory.
>
>Thanks
>Vivek

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