Re: [PATCHv4 3/4] x86/boot/compressed/64: Introduce place_trampoline()

[Ingo Molnar]

* Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> wrote:

> On Thu, Dec 07, 2017 at 07:30:48AM +0100, Ingo Molnar wrote:
> > > We also need a small stack in the trampoline to re-enable long mode via
> > > long return. But stack and code can share the page just fine.
> > 
> > BTW., I'm not sure this is necessarily a good idea: it means writable+executable 
> > memory, which we generally try to avoid. How complicated would it be to have them 
> > separate?
> 
> It's trivial: you only need to bump TRAMPOLINE_32BIT_SIZE.
> 
> But it doesn't make much sense. We're running from indentity mapping: all
> memory is r/w without NX bit set (and IA32_EFER.NXE is 0).

Ok, fair enough!

Thanks,

	Ingo