Thread (24 messages) 24 messages, 4 authors, 2019-09-18

Re: [PATCH v7 5/6] powerpc/64: Make COMPAT user-selectable disabled on littleendian by default.

From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2019-09-02 23:54:05
Also in: linux-fsdevel, lkml

Segher Boessenkool [off-list ref] writes:
On Mon, Sep 02, 2019 at 12:03:12PM +1000, Michael Ellerman wrote:
quoted
Michal Suchanek [off-list ref] writes:
quoted
On bigendian ppc64 it is common to have 32bit legacy binaries but much
less so on littleendian.
I think the toolchain people will tell you that there is no 32-bit
little endian ABI defined at all, if anything works it's by accident.
                ^
                v2
There of course is a lot of powerpcle-* support.  The ABI used for it
on linux is the SYSV ABI, just like on BE 32-bit.
I was talking about ELFv2, which is 64-bit only. But that was based on
me thinking we had a hard assumption in the kernel that ppc64le kernels
always expect ELFv2 userland. Looking at the code though I was wrong
about that, it looks like we will run little endian ELFv1 binaries,
though I don't think anyone is testing it.
There also is specific powerpcle-linux support in GCC, and in binutils,
too.  Also, config.guess/config.sub supports it.  Half a year ago this
all built fine (no, I don't test it often either).

I don't think glibc supports it though, so I wonder if anyone builds an
actual system with it?  Maybe busybox or the like?
quoted
So I think we should not make this selectable, unless someone puts their
hand up to say they want it and are willing to test it and keep it
working.
What about actual 32-bit LE systems?  Does anyone still use those?
Not that I've ever heard of.

cheers
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