Uros Bizjak wrote:
On Thu, Mar 13, 2008 at 2:35 PM, Joel Sherrill
<[EMAIL PROTECTED]> wrote:
I hacked on that test program to get the attached
program. I ran it multiple times on qemu.
ext=0x0 sig=0x756e6547
0x781abfd YES on SSE2
I am now printing the return value from __get_cpuid_max()
ext=0x0 sig=0x756e6547 returned=0x2
0x781abfd YES on SSE2
Isn't the "sig" supposed to be >= 0x80000000?
I ran the same program natively and got this:
ext=0x0 sig=0x756e6547
0xbfebfbff YES on SSE2
I wonder if qemu is just reporting things wrong. :(
I searched the qemu manual and googled some but
didn't see anything that jumped out.
Does this look like qemu reporting a bogus cpuid or
gcc not parsing it correctly?
This all depends on the return value of __get_cpuid_max(). It returns
max value of base cpuid level (5 in my case), and shoould return 0 if
cpuid is not supported. This follows the procedure outlined in
http://download.intel.com/design/processor/applnots/24161832.pdf,
section 2: "Detecting the CPUID Instruction".
I added a print before the return on !__get_cpuid and it is returning
non-zero.
It is true, that this is not the most maintained code on the planet,
so some bitrot is possible. The return value of __get_cpuid_max() on
your target will tell...
The call to __get_cpuid is checking against level 1 and this is a level 2.
--joel
Thanks,
Uros.
--
Joel Sherrill, Ph.D. Director of Research & Development
[EMAIL PROTECTED] On-Line Applications Research
Ask me about RTEMS: a free RTOS Huntsville AL 35805
Support Available (256) 722-9985
