lkml.org 
[lkml]   [2008]   [Jun]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Various x86 syscall mechanisms
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


\
 
 \ /
  Last update: 2008-06-21 04:03    [W:0.374 / U:0.072 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site