Messages in this thread | | | Date | Mon, 28 Sep 2015 08:20:15 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME regions |
| |
* Borislav Petkov <bp@alien8.de> wrote:
> On Sun, Sep 27, 2015 at 09:06:44AM +0200, Ingo Molnar wrote: > > > Could we please re-list all the arguments pro and contra of 1:1 physical > > mappings, in a post that also explains the background so that more people can > > chime in, not just people versed in EFI internals? It's very much possible > > that a bad decision was made. > > The main reason why we did the additional, top-down mapping was kexec kernel > wanting to use UEFI runtime facilities too and the braindead design of > SetVirtualAddressMap() being callable only once per system boot. So we had to > have stable mappings which are valid in the kexec-ed kernel too. > > But this was long time ago and I most certainly have forgotten all the details. > > And now I'm wondering why didn't we do the 1:1 thing and rebuild the exact same > EFI pagetable in the kexec-ed kernel? Because when we do an EFI call, we switch > to the special pagetable so why didn't we make the kexec-ed kernel rebuild the > 1:1 pagetable which it can use for EFI calls...
Yeah.
> Hmm, again, I've forgotten a lot of details so I'm sure Matt will come in and > say "No, you can't do that because..."
Would be nice to re-examine all this.
Thanks,
Ingo
| |