[ipxe-devel] cpuid-flags in cpuid.h maybe incomplete?

Michael Brown mcb30 at ipxe.org
Sun Apr 20 21:09:47 BST 2014


On 19/04/14 09:53, Oliver Rath wrote:
> I try to test some flag in ipxe script. If i see right (depending on
> https://git.ipxe.org/mirror/memtest.git/blame/1abd405570a2692adcc3bef3845bfb9178a1d952:/cpuid.h),
> the following flag are recognized in this way:
>
> cpuid --ext 6  = PAE Support
> cpuid 26       = SSE2 Support
> cpuid --ext 20 = NX Support
>
> Is this correct?

You can follow the links on http://ipxe.org/cmd/cpuid to get the full 
list of x86 CPUID flags.  The "cpuid" command doesn't understand what 
the flags mean; it just provides a way to test numbered bits of the flags.

> Reffering the cpuid.h file line 166 = bit 0, line 196 = bit 31, but
> 166+31=197, so there seems one bit omitted, but Im not sure, that Im
> allowed to relate in this way.

Observe line 184.

Michael


More information about the ipxe-devel mailing list