Re: [patch] paravirt: VDSO page is essential

Zachary Amsden
2007-03-05T20:42:26Z

Ingo Molnar wrote:
> there's no need to disable the VDSO for old userspace ...
>

Well, apart from the obvious question to which nobody actually knows the
answer, (how many people run old user space that required
CONFIG_COMPAT_VDSO), what do you think of reversing the boot option?

vdso=enabled (default - turn on VDSO on normal boots)
vdso=disabled (turn off VDSO unconditionally)
[vdso=compat] (default for COMPAT_VDSO - keep VDSO only when mapped at
compat location. Note the option is not required to be implemented
because it is logically implied from vdso=enabled && COMPAT_VDSO and the
default boot behavior)
vdso=force (keep VDSO even when moved to a new location and COMPAT_VDSO
is enabled).

In our case, installing VMware tools in the guest would then detect if
userspace supports VDSO or if it requires COMPAT_VDSO and would then set
boot parameters for the kernel appropriately. And the native boot and
kvm paravirt-ops boot are completely unaffected.

Zach