[U-Boot] [PATCH v2 3/3] x86: Test mtrr support flag before accessing mtrr msr

[Simon Glass]

On 21 January 2015 at 20:29, Bin Meng <bmeng.cn at gmail.com> wrote:
> On some x86 processors (like Intel Quark) the MTRR registers are not
> supported. This is reflected by the CPUID (EAX 01H) result EDX[12].
> Accessing the MTRR registers on such processors will cause #GP so we
> must test the support flag before accessing MTRR MSRs.
>
> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
>
> ---
>
> Changes in v2:
> - Return -ENOSYS in mtrr_commit() and mtrr_add_request() when MTRR MSR
>   is not implemented in the processor
> - Add return value description of mtrr_commit() and mtrr_add_request()
> - Ignore -ENOSYS in init_cache_f_r() in arch/x86/lib/init_helpers.c
>
>  arch/x86/cpu/mtrr.c         | 12 ++++++++++++
>  arch/x86/include/asm/mtrr.h |  5 ++++-
>  arch/x86/lib/init_helpers.c |  4 +++-
>  3 files changed, 19 insertions(+), 2 deletions(-)

Acked-by: Simon Glass <sjg at chromium.org>