[yocto] Is linux-yocto-rt kernel compatible with x32 tune?

[Andre McCurdy]

On Wed, Jun 14, 2017 at 11:13 PM, Bruce Ashfield
<bruce.ashfield at gmail.com> wrote:
> On Thu, Jun 15, 2017 at 4:11 AM, Paul D. DeRocco <pderocco at ix.netcom.com>
> wrote:
>>
>> I've been fighting with this off and on for a week. If I build
>> core-image-minimal for a generic86-64 machine, I can get it to use the x32
>> ABI, or I can switch to the linux-yocto-rt 4.8 kernel, but I can't do
>> both.
>>
>> If I do both, it builds with no complaint other than a lot of bit size
>> errors in grub-efi do_package_qa (which don't seem to matter with the
>> standard kernel). Most binaries, including loadable kernel modules, are
>> properly built as ELF architecture i386:x64-32, but the kernel itself is
>> built as i386:x86-64. The result is an immediate kernel panic trying to
>> run init, because the kernel doesn't know how to load it.

Isn't the point of x32 that the kernel should be full 64bit (and so
able to directly address all memory) and only user space should be
restricted to 32bit pointers?

If so, then the kernel ELF architecture x86-64 seems correct. If that
kernel can't run x32 user space binaries then maybe the kernel config
option to enable support for x32 user space is somehow missing?

>>
>> I understand that not all packages have been updated to work with x32, but
>> the RT kernel? Is this a combination that is known not to work? If it is
>> expected to work, am I the first person to try to boot it on actual
>> hardware? I'd like to know either that this simply won't work, so I can
>> stop wasting time on it, or get some help diagnosing the problem and
>> fixing it. I'm stumped.
>
>
> I can't think of a reason off the top of my head that would prevent this
> from working at the kernel level.
>
> But can you confirm that a non-rt build for the same board works with
> x32 ? It could just be a kernel configuration issue if it does work with
> non-rt, since the -rt variant may not have a BSP entry point defined.
>
> Bruce
>
>>
>>
>> --
>>
>> Ciao,               Paul D. DeRocco
>> Paul                mailto:pderocco at ix.netcom.com
>>
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>
>
>
> --
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