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Date: Wed, 20 Dec 2023 21:27:32 +0800
From: Baoquan He <bhe@redhat.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: kernel test robot <lkp@intel.com>, oe-kbuild-all@lists.linux.dev,
	linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: arch/sh/kernel/relocate_kernel.S:38: Error: invalid operands for
 opcode
Message-ID: <ZYLrxFyei79R5D8N@MiWiFi-R3L-srv>
References: <202312182200.Ka7MzifQ-lkp@intel.com>
 <ZYJ/M1HZ9ITfs4qe@MiWiFi-R3L-srv>
 <20231220060030.GV1674809@ZenIV>
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In-Reply-To: <20231220060030.GV1674809@ZenIV>

On 12/20/23 at 06:00am, Al Viro wrote:
> On Wed, Dec 20, 2023 at 01:44:19PM +0800, Baoquan He wrote:
> 
> > >    arch/sh/kernel/relocate_kernel.S: Assembler messages:
> > > >> arch/sh/kernel/relocate_kernel.S:38: Error: invalid operands for opcode
> > >    arch/sh/kernel/relocate_kernel.S:41: Error: invalid operands for opcode
> > >    arch/sh/kernel/relocate_kernel.S:126: Error: invalid operands for opcode
> > >    arch/sh/kernel/relocate_kernel.S:129: Error: invalid operands for opcode
> > 
> > I reproduced this error, haven't got why and a way to fix it, will come
> > back later if I have fix.
> 
> At a guess - after that commit ARCH_SUPPORTS_CRASH_DUMP is enough to enable CRASH_DUMP,
> which selects KEXEC_CORE regardless of ARCH_SUPPORTS_KEXEC.  And on sh you have
> the former selected on any UP build, while the latter - only on MMU ones (i.e.
> not SH2).

Yeah, you are right. I managed to set CONFIG_CPU_SH4=y and CONFIG_MMU=y,
the building passed.
---------------------
CONFIG_CPU_SH4=y
CONFIG_CPU_SH4A=y
CONFIG_CPU_SHX2=y
...
CONFIG_MMU=y
...
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_CRASH_DUMP=y
-----------------------------

Since the kexec_core code building depends on CONFIG_MMU=y, we may
need to add dependency on MMU for ARCH_SUPPORTS_CRASH_DUMP. I made below
change, do you think it's OK?

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 7500521b2b98..fe1500871648 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -548,6 +548,7 @@ config ARCH_SUPPORTS_KEXEC
 
 config ARCH_SUPPORTS_CRASH_DUMP
        def_bool BROKEN_ON_SMP
+       depends on MMU
 
 config ARCH_SUPPORTS_KEXEC_JUMP
        def_bool y