linux-kernel - Re: [PATCH 1/2] UEFI arm64: add noefi boot param

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Message-ID: <20140807012708.GA20295@darkstar.nay.redhat.com>
Date:	Thu, 7 Aug 2014 09:27:09 +0800
From:	Dave Young <dyoung@...hat.com>
To:	Matt Fleming <matt@...sole-pimps.org>
Cc:	Leif Lindholm <leif.lindholm@...aro.org>, catalin.marinas@....com,
	will.deacon@....com, matt.fleming@...el.com,
	ard.biesheuvel@...aro.org, msalter@...hat.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-efi@...r.kernel.org
Subject: Re: [PATCH 1/2] UEFI arm64: add noefi boot param

On 08/06/14 at 03:01pm, Matt Fleming wrote:
> On Wed, 06 Aug, at 02:29:41PM, Leif Lindholm wrote:
> > On Wed, Aug 06, 2014 at 02:20:21PM +0100, Matt Fleming wrote:
> > > > Since this is really turning an x86-specific feature into a generic
> > > > one, could it be moved to core code?
> > > > Maybe an efi.mask, reusing the efi_enabled defines, with an
> > > > efi_disabled macro?
> > >  
> > > Why the new efi_disabled() and efi.mask? This is all achievable with
> > > efi_enabled() and efi.flags, in fact, this kind of thing is exactly why
> > > they were invented.
> > 
> > Because this flag is indicating which facilities we should not try to
> > enable, rather than which facilities we have enabled.
> > 
> > The EFI_RUNTIME_SERVICES flag is set after successful call to
> > set_virtual_address_map. The apparent intent of "noefi" is to prevent
> > that call from being made in the first place.
> > 
> > Anyway, it was just a suggestion - main point was it would make sense
> > to share the code.
> 
> Definitely.
> 
> Dave, below is the kind of thing that I had in mind. Please Cc the Xen
> and SGI folks when you submit your next version because they're likely
> to be hit the hardest by any changes to EFI_RUNTIME_SERVICES and
> "noefi".
> 
> Obviously the addition of "efi=noruntime" is needed on top, but that's
> about 6 lines of code.

[snip]

Matt, will file a new version based on your code. I will also address the
failure case in enter virtual mode.

Currently in x86, there's cases such as efi_map_regions failure and efi call
set_virtual_address_map, in case those failures it should be better to
unset the EFI_RUNTIME_SERVICES in efi.flags instead of do noting or panic.

As for Xen and SGI people? I have not been following all the efi threads
so I'm not sure who exactly I should cc, could you tell me? 


Thanks
Dave
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