Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [RFC PATCH] MIPS: Kconfig: Select ARCH_WANT_FRAME_POINTERS
To:     Tiezhu Yang <yangtiezhu@loongson.cn>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc:     linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
        Xuefeng Li <lixuefeng@loongson.cn>
References: <1605502980-31946-1-git-send-email-yangtiezhu@loongson.cn>
From:   Sergei Shtylyov <sergei.shtylyov@gmail.com>
Organization: Brain-dead Software
Message-ID: <62ea9838-70ce-ca73-7dae-e94620956ab5@gmail.com>
Date:   Mon, 16 Nov 2020 12:08:26 +0300
User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:78.0) Gecko/20100101
 Thunderbird/78.4.3
MIME-Version: 1.0
In-Reply-To: <1605502980-31946-1-git-send-email-yangtiezhu@loongson.cn>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

Hello!

On 16.11.2020 8:03, Tiezhu Yang wrote:

> Select ARCH_WANT_FRAME_POINTERS to fix the following build error under
> CONFIG_DEBUG_ATOMIC_SLEEP:
> 
>    CC      arch/mips/kernel/signal.o
> {standard input}: Assembler messages:
> {standard input}:1775: Error: Unable to parse register name $fp
> scripts/Makefile.build:283: recipe for target 'arch/mips/kernel/signal.o' failed
> make[2]: *** [arch/mips/kernel/signal.o] Error 1
> scripts/Makefile.build:500: recipe for target 'arch/mips/kernel' failed
> make[1]: *** [arch/mips/kernel] Error 2
> Makefile:1799: recipe for target 'arch/mips' failed
> make: *** [arch/mips] Error 2
> 
> I think it is useful to get debugging information as described in the
> following texts:
> 
> lib/Kconfig.debug
> config FRAME_POINTER
>          bool "Compile the kernel with frame pointers"
>          ...
>          default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
>          help
>            If you say Y here the resulting kernel image will be slightly
>            larger and slower, but it gives very useful debugging information
>            in case of kernel bugs. (precise oopses/stacktraces/warnings)
> 
> Documentation/dev-tools/kgdb.rst
> This option inserts code to into the compiled executable which saves

    So to or into? :-)

> the frame information in registers or on the stack at different points
> which allows a debugger such as gdb to more accurately construct stack
> back traces while debugging the kernel.
> 
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
[...]

MBR, Sergei