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Re: [PATCH v2] [BZ #10283] localedef: align fixed maps to SHMLBA


On 05/28/2013 04:26 PM, David Miller wrote:
> From: "Carlos O'Donell" <carlos@redhat.com>
> Date: Tue, 28 May 2013 16:20:22 -0400
> 
>> I know it's a little pedantic, but it's not a generic issue, and thus I
>> agree that it should be a part of the OS/hardware support code.
> 
> Any OS which allows illegal cache aliases to be created as a result of
> an MMAP call is broken, they signal an error instead.
> 
> The standard way to express the required alignment in every single case
> I am aware of is SHMLBA.
> 
> And that's why Linux "inherited" this semantic from other systems.

Thanks for the background.

It's unfortunate that POSIX doesn't say more than just:
"If MAP_FIXED is specified, the implementation may require that 
addr is a multiple of the page size."

Perhaps we'll get Issue 8 to say something about SHMLBA in the
non-normative RATIONALE section for mmap.

Cheers,
Carlos.


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