Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 25 Aug 2003 05:05:14 +0100 | From | Jamie Lokier <> | Subject | Re: [PATCH] Pentium Pro - sysenter - doublefault |
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Jim Houston wrote: > On my cpu model=1 and mask=9, it doesn't clear 86_FEATURE_SEP. > This results in a double-fault when init starts. The double-fault > happens on the sysexit. The new double-fault handler caught this > nicely, and I was able to debug this with kgdb.
Does anyone know what the syenter & sysexit instructions do on these early PPro CPUs?
The Intel documentation is vague, saying only to avoid using them. I'd like to know what happens if userspace does "sysenter" on one of these systems. Does it issue Invalid Opcode, General Protection fault, or something else?
Jim you can answer this as you have such a Ppro. Could you please run this very simple userspace program for me, and report the result?
int main() { __asm__ ("sysenter"); return 0; }
I expect it to die with SIGILL on Pentium and earlier chips, and SIGSEGV on "good" PPro and later chips running kernels which don't enable the sysenter instruction.
But what does it do on your early Intel PPro, the one which is the subject of this thread?
Thanks, -- Jamie - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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