Messages in this thread | | | Date | Mon, 22 Aug 2011 11:53:37 +0200 | From | Ingo Molnar <> | Subject | Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) |
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* H. Peter Anvin <hpa@zytor.com> wrote:
> 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.
Last i measured INT80 and SYSCALL costs they were pretty close to each other on AMD CPUs - closer than on Intel.
Also, most installations are either pure 32-bit or dominantly 64-bit, the significantly mixed-mode case is dwindling.
Unifying some more in this area would definitely simplify things ...
Thanks,
Ingo
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