On 1/19/2015 12:21 PM, Borislav Petkov wrote:
On Mon, Jan 19, 2015 at 12:18:58PM -0600, Aravind Gopalakrishnan wrote:
The NodeId field in cpuid_ecx(0x8000001e) is a 8 bit field.
Although current extractor works fine, it will break if/when
the most significant 5 bits ever get used.
So, lets honor the field as architected in the BKDG
Reference: BKDG for AMD Fam15h Models 00h-0fh,
CPUID Fn8000_001E_ECX Node Identifiers
Signed-off-by: Aravind Gopalakrishnan <aravind.gopalakrish...@amd.com>
---
arch/x86/kernel/cpu/amd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index a220239..9942b83 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -300,7 +300,7 @@ static void amd_get_topology(struct cpuinfo_x86 *c)
cpuid(0x8000001e, &eax, &ebx, &ecx, &edx);
nodes = ((ecx >> 8) & 7) + 1;
- node_id = ecx & 7;
+ node_id = ecx & 0xff;
That's {00000b,D18F0x60[NodeId]} and NodeId is 3 bits for enumerating
8 nodes so checking the 3 bits is actually correct as it says that the
other 5 are 0b.
Right. Just a concern that if the definition of those 5 bits changes
then it would be a problem.
Regardless, is this something hypothetical you've noticed from code
inspection or are we really going to have more than 8 nodes? If the
former, then patch is unnecessary churn.
Just something from code inspection. So not an immediate issue.
Thanks,
-Aravind.
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