Re: PATCH: Add x32_corenote.c

[Mark Wielaard <mjw at redhat dot com>]

On Tue, 2015-03-24 at 07:45 -0700, H.J. Lu wrote:
> On Tue, Mar 24, 2015 at 6:48 AM, Mark Wielaard <mjw@redhat.com> wrote:
> > I don't see a gabi processor supplement for x32 here:
> > http://refspecs.linuxbase.org/elf/index.html
> > Do you know where it is kept?
> 
> http://www.x86-64.org/svn/trunk/x86-64-ABI/

Aha, it really is just ILP32 for x86_64. The only really tricky part
seems to make sure you zero-extend any 32bit addresses. Thanks.

> > Are there any distros using x32 to run some tests on?
> 
> Ubuntu 14.02.

I am not too familiar with Ubuntu. Do you happen to have a direct
download link for the specific installer to use? Does it have a full x32
user land and toolchain that defaults to it, or do you need to install
or configure anything specific to get a x32 setup?

> > Is x32 really completely similar to x86_64 to not need its own
> > backend/x32_init.c? I am surprised all of the other backend hooks don't
> > need similar tweaks to the core_note one.
> 
> X32 is very similar to x86-64.  The main difference is ELF class.
> All other backends similar x32 have
> 
> ppc64_corenote.c:#include "ppc_corenote.c"
> s390x_corenote.c:#include "s390_corenote.c"
> sparc64_corenote.c:#include "sparc_corenote.c"

Yes, but for ppc and ppc64 for example are separate backends that just
happen to share some of the backend hooks. And s390 does hook more than
just corenote differently between the 32 and 64 classes. I was just
surprised only corenote needed to be tweaked for x32 and nothing else.

But I guess it really is just x86_64 with zero-extended 32bit addresses,
so almost everything really is the same.

Thanks,

Mark