xen64: disable 32-bit syscall/sysenter if not supported.

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Old versions of Xen (3.1 and before) don't support sysenter or syscall
from 32-bit compat userspaces.  If we can't set the appropriate
syscall callback, then disable the corresponding feature bit, which
will cause the vdso32 setup to fall back appropriately.

Linux assumes that syscall is always available to 32-bit userspace,
and installs it by default if sysenter isn't available.  In that case,
we just disable vdso altogether, forcing userspace libc to fall back
to int $0x80.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

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This commit is contained in:

Jeremy Fitzhardinge 2008-07-10 16:24:08 -07:00 • committed by Ingo Molnar

parent 6596f24223

commit 62541c3766

1 changed files with 19 additions and 19 deletions

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arch/x86/xen/setup.c

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