Hi Simon,
On Thu, Jan 22, 2015 at 12:06 AM, Simon Glass <s...@chromium.org> wrote:
> Hi Bin,
>
> On 19 January 2015 at 22:01, Bin Meng <bmeng...@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...@gmail.com>
>> ---
>>
>> arch/x86/cpu/mtrr.c | 12 ++++++++++++
>> 1 file changed, 12 insertions(+)
>>
>> diff --git a/arch/x86/cpu/mtrr.c b/arch/x86/cpu/mtrr.c
>> index ac8765f..68f1b04 100644
>> --- a/arch/x86/cpu/mtrr.c
>> +++ b/arch/x86/cpu/mtrr.c
>> @@ -22,6 +22,9 @@ DECLARE_GLOBAL_DATA_PTR;
>> /* Prepare to adjust MTRRs */
>> void mtrr_open(struct mtrr_state *state)
>> {
>> + if (!gd->arch.has_mtrr)
>> + return;
>> +
>> state->enable_cache = dcache_status();
>>
>> if (state->enable_cache)
>> @@ -33,6 +36,9 @@ void mtrr_open(struct mtrr_state *state)
>> /* Clean up after adjusting MTRRs, and enable them */
>> void mtrr_close(struct mtrr_state *state)
>> {
>> + if (!gd->arch.has_mtrr)
>> + return;
>> +
>> wrmsrl(MTRR_DEF_TYPE_MSR, state->deftype | MTRR_DEF_TYPE_EN);
>> if (state->enable_cache)
>> enable_caches();
>> @@ -45,6 +51,9 @@ int mtrr_commit(bool do_caches)
>> uint64_t mask;
>> int i;
>>
>> + if (!gd->arch.has_mtrr)
>> + return 0;
>> +
>> mtrr_open(&state);
>> for (i = 0; i < gd->arch.mtrr_req_count; i++, req++) {
>> mask = ~(req->size - 1);
>> @@ -66,6 +75,9 @@ int mtrr_add_request(int type, uint64_t start, uint64_t
>> size)
>> struct mtrr_request *req;
>> uint64_t mask;
>>
>> + if (!gd->arch.has_mtrr)
>> + return 0;
>
> Shouldn't this (and the above) return -ENOSYS?
If returning non-zero, the init_cache_f_r() will fail as it checks the
return value. Do you think we should ignore the return value there?
But if ignored, there is no meaning of returning error codes here.
>> +
>> if (gd->arch.mtrr_req_count == MAX_MTRR_REQUESTS)
>> return -ENOSPC;
>> req = &gd->arch.mtrr_req[gd->arch.mtrr_req_count++];
>> --
>> 1.8.2.1
>>
>
> Regards,
> Simon
Regards,
Bin
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