linux-kernel - Re: [PATCH] export efi.flags to sysfs

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Message-ID: <CAL01qpuNS0u89gaR9pCKUoCVRkADhPO4mZueEyK8nP84=OfDaA@mail.gmail.com>
Date:	Thu, 29 May 2014 14:10:41 +0100
From:	"Fleming, Matt" <matt.fleming@...el.com>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	Dave Young <dyoung@...hat.com>, "bp@...en8.de" <bp@...en8.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>
Subject: Re: [PATCH] export efi.flags to sysfs

On 29 May 2014 13:59, Vivek Goyal <vgoyal@...hat.com> wrote:
>
> Only second kernel boots with "noefi" and this parameter is appened by
> kexec-tools to second kernel command line. So first kernel will still
> boot *without noefi* and kexec-tools wil think that this system support
> booting second kernel with UEFI enabled.
>
> I don't know if we export /sys/firmware/efi/runtime-map/ in case of
> non 1:1 mapping or not. Dave and Boris will know better.

Looking at the code the answer is: yes. I think that's the bug right there.

By exporting entries in /sys/firmware/efi/runtime-map we're saying
"These mappings persist across kexec, you can trust that they won't
change", for SGI UV (which currently uses the quirk) or if you boot
with efi=old_map on the command line, that's simply not true.

So, it would seem to me that we're missing a "if
(efi_enabled(OLD_MAP))" in drivers/firmware/efi/runtime-map.c.
Borislav, Dave? What do you guys think?

This is all assuming that the root of the regression is that
kexec-tools sees entries in /sys/firmware/efi/runtime-map/ and says
"Yay! EFI boot!".
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