[Buildroot] [PATCH 3/4] arch: do not distinguish revisions of ARM1136JF-S

Benoît Thébaudeau benoit.thebaudeau.dev at gmail.com
Mon Sep 15 22:36:48 UTC 2014


Dear Thomas Petazzoni,

On Mon, Sep 15, 2014 at 11:50 PM, Thomas Petazzoni
<thomas.petazzoni at free-electrons.com> wrote:
> Dear Benoît Thébaudeau,
>
> On Mon, 15 Sep 2014 23:44:52 +0200, Benoît Thébaudeau wrote:
>
>> >> As suggested on IRC, move the BR2_arm1136jf_s_r1 to Config.legacy, and
>> >> have it select BR2_arm1136jf_s, so the user can re-use a defconfig.
>> >
>> > Hum, why just BR2_arm1136jf_s_r1 and not BR2_arm1136jf_s_r0 ?
>>
>> This issue disappears if -march and -mtune are kept and -mcpu removed
>> as I suggested.
>
> Do you have an example C code that doesn't generate the same assembly
> code between BR2_arm1136jf_s_r0 and BR2_arm1136jf_s_r1 ? It would be
> useful for my testing.

The instructions supported by armv6k but not by armv6j are:
ldrex{h|b|d}, strex{h|b|d}, clrex, nop, sev, wfe, wfi and yield. This
is especially useful for handwritten assembler implementations (in .S,
or inline in .c) of some OS functions, typically atomic operations and
context switches.

Benoît


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