Bug#464962: Do AMD K7 family CPUs support long noops?
H. Peter Anvin wrote: i.e. can you safely enable X86_P6_NOP for other CPUs, such as AMD K7/K8, VIA C3/C7, or Efficeon? If not, would it be more sensible to avoid using these instructions? It appears that at least some VIA C3 CPUs do not support these opcodes: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=463606#45 Attached is a C program which tests this. [EMAIL PROTECTED]:~/src# cat /proc/cpuinfo processor : 0 vendor_id : CentaurHauls cpu family : 6 model : 13 model name : VIA C7-D Processor 1500MHz stepping: 0 cpu MHz : 1500.156 cache size : 128 KB fdiv_bug: no hlt_bug : no f00f_bug: no coma_bug: no fpu : yes fpu_exception : yes cpuid level : 1 wp : yes flags : fpu vme de pse tsc msr pae mce apic sep mtrr pge cmov pat clflush acpi mmx fxsr sse sse2 tm nx up pni xtpr rng rng_en ace ace_en ace2 ace2_en phe phe_en pmm pmm_en bogomips: 3002.28 clflush size: 64 [EMAIL PROTECTED]:~/src# ./longnop Long NOPs supported: yes -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Bug#464962: Do AMD K7 family CPUs support long noops?
Hello, I am wondering whether anyone has looked into which AMD CPUs support these instructions. I would think that installing a 486 kernel on an AthlonXP, for example, would be quite sub-optimal. i.e. can you safely enable X86_P6_NOP for other CPUs, such as AMD K7/K8, VIA C3/C7, or Efficeon? If not, would it be more sensible to avoid using these instructions? It appears that at least some VIA C3 CPUs do not support these opcodes: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=463606#45 -- graham -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Bug#464962: Do AMD K7 family CPUs support long noops?
Graham wrote:
Hello,
I am wondering whether anyone has looked into which AMD CPUs support
these instructions. I would think that installing a 486 kernel on an
AthlonXP, for example, would be quite sub-optimal.
i.e. can you safely enable X86_P6_NOP for other CPUs, such as AMD
K7/K8, VIA C3/C7, or Efficeon? If not, would it be more sensible to
avoid using these instructions?
It appears that at least some VIA C3 CPUs do not support these opcodes:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=463606#45
Attached is a C program which tests this.
#include stdio.h
#include signal.h
#include setjmp.h
static sigjmp_buf out;
void sigill(int signal)
{
siglongjmp(out, 1);
}
int main(void)
{
int died;
signal(SIGILL, sigill);
died = sigsetjmp(out, 1);
if (!died)
asm volatile(nopl 0(%eax));
printf(Long NOPs supported: %s\n, died ? no : yes);
return died;
}
Bug#464962: Do AMD K7 family CPUs support long noops?
If not, would it be more sensible to avoid using these instructions? Sorry, this question was not directed at Linux in general, but rather at Debian's generic 686 kernel. My thought was to allow the largest possible number of users to benefit from the 686 kernel, instead of forcing them to downgrade to a 486 kernel. -- graham -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Bug#464962: Do AMD K7 family CPUs support long noops?
On Wed, Feb 13, 2008 at 01:53:24PM -0800, H. Peter Anvin wrote: Graham wrote: Hello, I am wondering whether anyone has looked into which AMD CPUs support these instructions. I would think that installing a 486 kernel on an AthlonXP, for example, would be quite sub-optimal. i.e. can you safely enable X86_P6_NOP for other CPUs, such as AMD K7/K8, VIA C3/C7, or Efficeon? If not, would it be more sensible to avoid using these instructions? It appears that at least some VIA C3 CPUs do not support these opcodes: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=463606#45 Attached is a C program which tests this. Via Epia SP8000 (C3) Long NOPs supported: no [EMAIL PROTECTED]:~cat /proc/cpuinfo processor : 0 vendor_id : CentaurHauls cpu family : 6 model : 9 model name : VIA Nehemiah stepping: 8 Via Epia EN15000 (C7) Long NOPs supported: yes [EMAIL PROTECTED]:~cat /proc/cpuinfo processor : 0 vendor_id : CentaurHauls cpu family : 6 model : 10 model name : VIA Esther processor 1500MHz stepping: 9 Christian -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
