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

On 21 January 2015 at 20:29, Bin Meng bmeng.cn@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@gmail.com

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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@chromium.org