* Glauber de Oliveira Costa ([EMAIL PROTECTED]) wrote:
> Only caveat, is that it has to be done before smp gets in the game, and
> with interrupts disabled. (which makes the function in vsmp.c not eligible).
>
> My current option is to force VSMP to use PARAVIRT, as said before, and
> then fill paravirt_arch_setup, which is currently unused, with code to
> replace the needed paravirt_ops.fn.
>
> I don't know if there is any method to dynamically determine (at this
> point) that we are in a vsmp arch, and if there are not, it will have to
> get ifdefs anyway. But at least, they are far more local.
between __cacheline_aligned_in_smp and other compile time bits based on
VSMP specific INTERNODE_CACHE, etc. I think compile time the way to go.
> I am okay with both, but after all the explanation, I don't think that
> adding a new pvops is a bad idea. It would make things less cumbersome
> in this case. Also, hacks like this save_fl may require changes to the
> hypervisor, right? I don't even know where such hypervisor is, and how
> easy it is to replace it (it may be deeply hidden in firmware)
No hypervisor change needed. Just the pv backend needs to return 0 or
X86_EFLAGS_IF for save_flags (and similar translation on restore_flags).
Xen uses a simple shared memory flag and does something which you could
roughly translate into this:
xen_save_flags()
if (xen_vcpu_interrupts_enabled)
return X86_EFLAGS_IF;
else
return 0;
This doesn't require any hypervisor changes. Similarly, VSMP could do
something along the lines of:
vsmp_save_flags()
flags = native_save_flags();
if (flags & X86_EFLAGS_IF) || (flags & X86_EFLAGS_AC)
return X86_EFLAGS_IF;
else
return 0;
> A question raises here: Would vsmp turn paravirt_enabled to 1 ?
Probably not. It's mostly native and I'm not sure it would want the
bits disabled from if (paravirt_enabled()) tests.
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