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Subject: Re: [PATCH v2] um: Avoid longjmp/setjmp symbol clashes with
 libpthread.a
To: Florian Fainelli <f.fainelli@gmail.com>, linux-kernel@vger.kernel.org
References: <20170524003232.14319-1-f.fainelli@gmail.com>
 <cda59c31-1487-4c9d-8a6f-152caf93e1d3@gmail.com>
Cc: Jeff Dike <jdike@addtoit.com>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
        "open list:USER-MODE LINUX (UML)" 
        <user-mode-linux-devel@lists.sourceforge.net>,
        "open list:USER-MODE LINUX (UML)" 
        <user-mode-linux-user@lists.sourceforge.net>
From: Richard Weinberger <richard@nod.at>
Message-ID: <dbebd37c-bcae-14d9-445c-9f624008f9fb@nod.at>
Date: Mon, 5 Jun 2017 21:34:40 +0200
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Florian,

Am 05.06.2017 um 21:32 schrieb Florian Fainelli:
> On 05/23/2017 05:32 PM, Florian Fainelli wrote:
>> Building a statically linked UML kernel on a Centos 6.9 host resulted in
>> the following linking failure (GCC 4.4, glibc-2.12):
>>
>> /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/libpthread.a(libpthread.o):
>> In function `siglongjmp':
>> (.text+0x8490): multiple definition of `longjmp'
>> arch/x86/um/built-in.o:/local/users/fainelli/openwrt/trunk/build_dir/target-x86_64_musl/linux-uml/linux-4.4.69/arch/x86/um/setjmp_64.S:44:
>> first defined here
>> /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/libpthread.a(libpthread.o):
>> In function `sem_open':
>> (.text+0x77cd): warning: the use of `mktemp' is dangerous, better use
>> `mkstemp'
>> collect2: ld returned 1 exit status
>> make[4]: *** [vmlinux] Error 1
>>
>> Adopt a solution similar to the one done for vmap where we define
>> longjmp/setjmp to be kernel_longjmp/setjmp. In the process, make sure we
>> do rename the functions in arch/x86/um/setjmp_*.S accordingly.
>>
>> Fixes: a7df4716d195 ("um: link with -lpthread")
>> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> 
> Richard, we are kind of hijacking this thread now that was originally
> about statically linking UML, is this particular patch okay?

Hehe, yes.
This patch is good, I like it. :)
It will part of the next pull request.

Thanks,
//richard