From: Ralf Baechle <ralf@linux-mips.org>
To: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Cc: "Maciej W. Rozycki" <macro@linux-mips.org>,
Paul Burton <paulburton@kernel.org>,
James Hogan <jhogan@kernel.org>,
linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: build failure of mips decstation_r4k_defconfig with binutils-2_37
Date: Tue, 17 Aug 2021 14:55:09 +0200 [thread overview]
Message-ID: <YRuxrfYxahPbHmXl@linux-mips.org> (raw)
In-Reply-To: <YRujeISiIjKF5eAi@debian>
On Tue, Aug 17, 2021 at 12:54:32PM +0100, Sudip Mukherjee wrote:
> While I was testing v5.4.142-rc2 I noticed mips build of
> decstation_r4k_defconfig fails with binutils-2_37. The error is:
>
> arch/mips/dec/prom/locore.S: Assembler messages:
> arch/mips/dec/prom/locore.S:29: Error: opcode not supported on this
> processor: r4600 (mips3) `rfe'
>
> I have also reported this at https://sourceware.org/bugzilla/show_bug.cgi?id=28241
It would appear gas got more anal about ISA checking for the RFE instructions
which did only exist in MIPS I and II; MIPS III and later use ERET for
returning from an exception.
The older gas I've got installed here happily accepts RFE in MIPS III/R4000
mode:
$ cat s.s
rfe
eret
$ mips-linux-as -o s.o s.s
s.s: Assembler messages:
s.s:2: Error: opcode not supported on this processor: mips1 (mips1) `eret'
$ mips-linux-as -march=r4000 -o s.o s.s
$ mips-linux-objdump -d s.o
s.o: file format elf32-tradbigmips
Disassembly of section .text:
00000000 <.text>:
0: 42000010 c0 0x10 # <- RFE
4: 42000018 eret
...
$
It's easy to find arguments for why this gas change is the right thing to
do - and not the right thing to do.
It should be fixable by simply putting gas into mips1 mode. Can you test
below patch?
Ralf
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/dec/prom/locore.S b/arch/mips/dec/prom/locore.S
index 0eb8fab62ab0..8d00ca8872f9 100644
--- a/arch/mips/dec/prom/locore.S
+++ b/arch/mips/dec/prom/locore.S
@@ -16,6 +16,7 @@
NESTED(genexcept_early, 0, sp)
.set noat
.set noreorder
+ .set mips1
mfc0 k0, CP0_STATUS
la k1, mem_err
next prev parent reply other threads:[~2021-08-17 12:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-17 11:54 build failure of mips decstation_r4k_defconfig with binutils-2_37 Sudip Mukherjee
2021-08-17 12:55 ` Ralf Baechle [this message]
2021-08-17 13:33 ` Sudip Mukherjee
2021-08-17 13:47 ` Maciej W. Rozycki
2021-08-17 13:36 ` Maciej W. Rozycki
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