For some CPUID leaves (e.g. %eax=0x00000004), the result depends on
the input value of %ecx. Allow this subfunction number to be
specified as a parameter to the cpuid() wrapper.
The subfunction number is exposed via the ${cpuid/...} settings
mechanism using the syntax
${cpuid/<subfunction>.0x40.<register>.<function>}
e.g.
${cpuid/0.0x40.0.0x0000000b}
${cpuid/1.0x40.0.0x0000000b}
to retrieve the CPU topology information.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Allow CPUID values to be read using the syntax
${cpuid/<register>.<function>}
For example, ${cpuid/2.0x80000001} will give the value of %ecx after
calling CPUID with %eax=0x80000001. Values for <register> are encoded
as %eax=0, %ebx=1, %ecx=2, %edx=3.
The numeric encoding is more sophisticated than described above,
allowing for settings such as the CPU model (obtained by calling CPUID
with %eax=0x80000002-0x80000004 inclusive and concatenating the values
returned in %eax:%ebx:%ecx:%edx). See the source code for details.
The "cpuvendor" and "cpumodel" settings provide easy access to these
more complex CPUID settings.
This functionality is intended to complement the "cpuid" command,
which allows for testing individual CPUID feature bits.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Michael Brown