Messages in this thread | | | Date | Fri, 20 Jun 2008 19:00:33 -0700 | From | Jeremy Fitzhardinge <> | Subject | Re: Various x86 syscall mechanisms |
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H. Peter Anvin wrote: > The reason is that not all 64-bit processors (i.e. K8) support a > 32-bit sysenter in long mode (i.e. with a 64-bit kernel.)
OK, so compat 32-bit processes would use syscall in that case, even if they wouldn't on a 32-bit kernel?
> sysenter is *always* entered from the vdso, since the return address > is lost and this is also where a 64-bit kernel can put a syscall. > > There is no reason we couldn't do syscall for 32-bit native, but the > only processor that would benefit would be K7, and that's far enough > in the past that I don't think anyone cares enough.
OK, good.
> Note that long mode syscall is different from protected mode syscall, > even in 32-bit compatibility mode. The long mode variant is a lot saner.
You mean that syscall arriving in long mode ring0 is saner than syscall arriving in protected mode ring0?
J
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