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From: Michael Ellerman <mpe@ellerman.id.au>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Michal Suchanek <msuchanek@suse.de>,
	linuxppc-dev@lists.ozlabs.org,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Nicholas Piggin <npiggin@gmail.com>,
	Christophe Leroy <christophe.leroy@c-s.fr>,
	Breno Leitao <leitao@debian.org>, Arnd Bergmann <arnd@arndb.de>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Firoz Khan <firoz.khan@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Joel Stanley <joel@jms.id.au>,
	Hari Bathini <hbathini@linux.ibm.com>,
	Michael Neuling <mikey@neuling.org>,
	Andrew Donnellan <andrew.donnellan@au1.ibm.com>,
	Russell Currey <ruscur@russell.cc>,
	Diana Craciun <diana.craciun@nxp.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	David Hildenbrand <david@redhat.com>,
	Allison Randal <allison@lohutok.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	Madhavan Srinivasan <maddy@linux.vnet.ibm.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v7 5/6] powerpc/64: Make COMPAT user-selectable disabled on littleendian by default.
Date: Tue, 03 Sep 2019 09:53:56 +1000	[thread overview]
Message-ID: <87k1aqs19n.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20190902130008.GZ31406@gate.crashing.org>

Segher Boessenkool <segher@kernel.crashing.org> writes:
> On Mon, Sep 02, 2019 at 12:03:12PM +1000, Michael Ellerman wrote:
>> Michal Suchanek <msuchanek@suse.de> writes:
>> > 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?
>
>> 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

  reply	other threads:[~2019-09-02 23:54 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-30 21:03 [PATCH v7 0/6] Disable compat cruft on ppc64le v7 Michal Suchanek
2019-08-30 21:03 ` [PATCH v7 1/6] powerpc: Add back __ARCH_WANT_SYS_LLSEEK macro Michal Suchanek
2019-08-30 21:03 ` [PATCH v7 2/6] powerpc: move common register copy functions from signal_32.c to signal.c Michal Suchanek
2019-08-30 21:03 ` [PATCH v7 3/6] powerpc/perf: consolidate read_user_stack_32 Michal Suchanek
2019-09-02  3:53   ` Michael Ellerman
2019-09-02  4:01     ` Michael Ellerman
2019-09-02  8:26       ` Michal Suchánek
2019-09-02 23:45         ` Michael Ellerman
2019-08-30 21:03 ` [PATCH v7 4/6] powerpc/64: make buildable without CONFIG_COMPAT Michal Suchanek
2019-08-31  6:43   ` Christophe Leroy
2019-08-31 13:02   ` Michal Suchánek
2019-08-30 21:03 ` [PATCH v7 5/6] powerpc/64: Make COMPAT user-selectable disabled on littleendian by default Michal Suchanek
2019-09-02  2:03   ` Michael Ellerman
2019-09-02  9:42     ` Michal Suchánek
2019-09-03  0:00       ` Michael Ellerman
2019-09-14 10:22         ` Michal Suchánek
2019-09-18  5:36           ` Michael Ellerman
2019-09-02 13:00     ` Segher Boessenkool
2019-09-02 23:53       ` Michael Ellerman [this message]
2019-09-03  5:21         ` Christophe Leroy
2019-08-30 21:03 ` [PATCH v7 6/6] powerpc/perf: split callchain.c by bitness Michal Suchanek
2019-08-31 18:51   ` Michal Suchánek
2019-08-31  6:41 ` [PATCH v7 0/6] Disable compat cruft on ppc64le v7 Christophe Leroy
2019-08-31 18:03   ` Michal Suchánek

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