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

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Date:	Thu, 29 May 2014 08:59:10 -0400
From:	Vivek Goyal <vgoyal@...hat.com>
To:	"Fleming, Matt" <matt.fleming@...el.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 Thu, May 29, 2014 at 12:53:19PM +0100, Fleming, Matt wrote:
> On 28 May 2014 15:51, Vivek Goyal <vgoyal@...hat.com> wrote:
> > On Wed, May 28, 2014 at 10:09:35AM +0800, Dave Young wrote:
> >
> > [..]
> >> > I've only vaguely been following along with the other thread, so please
> >> > summarise everything again in your patch. Particularly, I need answers
> >> > to the following questions,
> >> >
> >> >  - Are you trying to fix a kexec/kdump regression?
> >>
> >> Somehow it is a regression.
> >
> > Well, it is a *regression*. Previously kdump would work with
> > SGI UV machines as it used "noefi". Now kexec by default thinks that
> > efi is enabled and 1:1 mappings are in place and that does not work
> > with SGI UV machines.
> 
> So, if someone boots an SGI UV machine with the "noefi" kernel command
> line parameter, the kernel still creates
> /sys/firmware/efi/runtime-map/ ? Why does kexec/kdump think a kernel
> booted with "noefi" supports EFI?
> 
> Or are we talking about a different "noefi" parameter?

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.

Thanks
Vivek
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