Re: SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weirdcrap with vdso on uml/i386)

[H. Peter Anvin]

Borislav,

We're tracking down an issue with the way system call arguments are
handled on 32 bits.  We have a solution for SYSENTER but not SYSCALL;
fixing SYSCALL "properly" appears to be very difficult at best.

So the question is: how much overhead would it be to simply fall back to
int $0x80 or some other legacy-style domain crossing instruction for
32-bit system calls on AMD64 processors?  We don't ever use SYSCALL in
legacy mode, so native i386 kernels are unaffected.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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