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

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Message-ID: <20140530015315.GA1985@darkstar.nay.redhat.com>
Date:	Fri, 30 May 2014 09:53:15 +0800
From:	Dave Young <dyoung@...hat.com>
To:	"Fleming, Matt" <matt.fleming@...el.com>
Cc:	Vivek Goyal <vgoyal@...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 05/29/14 at 02:10pm, Fleming, Matt wrote:
> 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?

Yes, I missed the old_map case when I did the patchset.
Only exporting runtime map in case 1:1 map looks good. Thus kexec-tools can
easily just check the existance of the sysfs files.

Will send out a patch soon.

Thanks
Dave
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