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Re: [committed, PATCH] Add -mshared option to x86 ELF assembler

On Mon, Jun 1, 2015 at 1:32 AM, Markus Trippelsdorf
<> wrote:
> On 2015.05.15 at 03:34 -0700, H.J. Lu wrote:
>> This patch adds -mshared option to x86 ELF assembler.  By default,
>> assembler will optimize out non-PLT relocations against defined non-weak
>> global branch targets with default visibility.  The -mshared option tells
>> the assembler to generate code which may go into a shared library
>> where all non-weak global branch targets with default visibility can
>> be preempted.  The resulting code is slightly bigger.  This option
>> only affects the handling of branch instructions.
>> This Linux kernel patch is needed to create a working x86 Linux kernel if
>> it hasn't been applied:
>> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
>> index ae6588b..b91a00c 100644
>> --- a/arch/x86/kernel/head_64.S
>> +++ b/arch/x86/kernel/head_64.S
>> @@ -339,8 +339,8 @@ early_idt_handlers:
>>       i = i + 1
>>       .endr
>> -/* This is global to keep gas from relaxing the jumps */
>> -ENTRY(early_idt_handler)
>> +/* This is weak to keep gas from relaxing the jumps */
>> +WEAK(early_idt_handler)
>>       cld
> Have you posted the patch to LKML already?
> (I hit this issue today and it took me a while to figure out the cause.)

A kernel patch will be checked in soon.


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