On Sun, May 19, 2019, 3:33 PM Olaf van der Spek <ml@xxxxxxxxxx> wrote: > On Sun, May 19, 2019 at 2:31 PM tedheadster <tedheadster@xxxxxxxxx> wrote: > > > > On Sun, May 19, 2019 at 7:31 AM Olaf van der Spek <ml@xxxxxxxxxx> wrote: > > > > > > What's eax after cpuid function 0? > > > > After calling cpuid function 0x0, %eax returns the expected 0x1. > > > > Here is the output of 'cpuid -r'. > > > > # cpuid -r > > CPU 0: > > 0x00000000 0x00: eax=0x00000001 ebx=0x746e6543 ecx=0x736c7561 > edx=0x48727561 > > 0x00000001 0x00: eax=0x00000585 ebx=0x746e6543 ecx=0x00000000 > edx=0x008001b5 > > ecx does contain 0 doesn't it? Or is this the wrong line? > > Olaf > I was fooled by that too. The /usr/bin/cpuid program is not the same as the gcc cpuid.h calls. I inserted debugging code and found that the %ecx register still had its part of the vendor string 'auls' in it (from 'CentaurHauls') from the earlier call to cpuid() with eax = 0. I posted a patch to the gcc-patches mailing list. - Matthew
