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From: Nicholas Piggin <npiggin@gmail.com>
To: Rich Felker <dalias@libc.org>, "Dmitry V. Levin" <ldv@altlinux.org>
Cc: Joakim Tjernlund <Joakim.Tjernlund@infinera.com>,
	linux-api@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	Michael Ellerman <mpe@ellerman.id.au>,
	musl@lists.openwall.com,
	Segher Boessenkool <segher@kernel.crashing.org>
Subject: [musl] Re: Linux powerpc new system call instruction and ABI
Date: Thu, 20 May 2021 12:45:57 +1000	[thread overview]
Message-ID: <1621478448.743zqcrxza.astroid@bobo.none> (raw)
In-Reply-To: <20210520010612.GA25599@altlinux.org>

Excerpts from Dmitry V. Levin's message of May 20, 2021 11:06 am:
> On Wed, May 19, 2021 at 07:48:47PM -0400, Rich Felker wrote:
>> On Wed, May 19, 2021 at 06:09:25PM +0000, Joakim Tjernlund wrote:
> [...]
>> > W.r.t breaking ABI, isn't that what PowerPC is trying to do with the new syscall I/F? 
>> 
>> No, it's a new independent interface.
> 
> Unfortunately, being a new independent interface doesn't mean it isn't
> an ABI break.  In fact, it was a severe ABI break, and this thread is
> an attempt to find a hotfix.

It is an ABI break, that was known. The ptrace info stuff I fixed with 
the patch earlier was obviously a bug in my initial implementation and 
not intended (sorry my ptrace testing was not sufficient, and thanks for
reporting it, by the way).

But the register ABI was always a known break. The issue is that rfscv
clobbers LR, so it can not support the old ABI. If the old ABI did not 
preserve LR, then we may have chosen to not change register ABI at all.

Thanks,
Nick

  reply	other threads:[~2021-05-20  2:46 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-11  8:12 [musl] " Nicholas Piggin
2020-06-11  8:12 ` [musl] [PATCH 1/2] powerpc/64s/exception: treat NIA below __end_interrupts as soft-masked Nicholas Piggin
2020-07-24 13:25   ` [musl] " Michael Ellerman
2020-06-11  8:12 ` [musl] [PATCH 2/2] powerpc/64s: system call support for scv/rfscv instructions Nicholas Piggin
2020-07-23  6:47   ` [musl] " Michael Ellerman
2020-07-23 16:48     ` Christophe Leroy
2020-07-24 10:45       ` Michael Ellerman
2020-06-11 21:02 ` [musl] Re: Linux powerpc new system call instruction and ABI Segher Boessenkool
2020-06-14  9:26   ` Nicholas Piggin
2021-05-18 23:13 ` Dmitry V. Levin
2021-05-19  2:50   ` Nicholas Piggin
2021-05-19  5:01     ` Nicholas Piggin
2021-05-21 19:40       ` Matheus Castanho
2021-05-21 19:52         ` Florian Weimer
2021-05-21 20:00           ` Matheus Castanho
2021-05-21 20:52             ` Dmitry V. Levin
2021-05-24 12:11               ` Matheus Castanho
2021-05-24 20:33                 ` Matheus Castanho
2021-05-19 10:24     ` Dmitry V. Levin
2021-05-19 10:59       ` Nicholas Piggin
2021-05-19 12:39         ` Tulio Magno Quites Machado Filho
2021-05-19 13:26         ` Dmitry V. Levin
2021-05-19 22:51           ` Nicholas Piggin
2021-05-19 23:27             ` Dmitry V. Levin
2021-05-20  2:40               ` Nicholas Piggin
2021-05-20  3:06                 ` Dmitry V. Levin
2021-05-20  5:12                   ` Nicholas Piggin
2021-05-19  7:33   ` Joakim Tjernlund
2021-05-19  7:55     ` Nicholas Piggin
2021-05-19  8:08       ` Joakim Tjernlund
2021-05-19  8:42         ` Nicholas Piggin
2021-05-19 11:12           ` Nicholas Piggin
2021-05-19 14:38           ` Segher Boessenkool
2021-05-19 15:06             ` Joakim Tjernlund
2021-05-19 15:22               ` Segher Boessenkool
2021-05-19 15:36                 ` Rich Felker
2021-05-19 18:09                 ` Joakim Tjernlund
2021-05-19 23:48                   ` Rich Felker
2021-05-20  1:06                     ` Dmitry V. Levin
2021-05-20  2:45                       ` Nicholas Piggin [this message]
2021-05-20  2:59                         ` Dmitry V. Levin
2021-05-20  7:20                           ` Nicholas Piggin

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