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

[Kirill A. Shutemov]

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).

-- 
 Kirill A. Shutemov