lkml.org 
[lkml]   [2014]   [Jan]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH v4 4/5] arm: Add [U]EFI runtime services support
Date
On Tuesday 14 January 2014, Leif Lindholm wrote:
> On Tue, Jan 14, 2014 at 07:52:32AM +0100, Arnd Bergmann wrote:
> > > > > It uses the generic configuration table scanning to populate ACPI and
> > > > > SMBIOS pointers.
> > > >
> > > > As far as I'm concerned there are no plans to have ACPI support on ARM32,
> > > > so I wonder what the code to populate the ACPI tables is about. Can
> > > > you clarify this?
> > >
> > > Are you suggesting that I should #ifndef ARM in common code, or that I
> > > should neglect to document what the common code will do with data it is
> > > given by UEFI?
> >
> > It would probably be good to document the fact that it won't work,
> > possibly even having a BUG_ON statement in the code for this case.
>
> Why?
>
> You'll only touch that pointer if you enable CONFIG_ACPI, and if you
> do you probably want that address. Sounds a bit hostile to throw a BUG
> in the face of someone who's (for example) just succeeded to get Linux
> running on a Windows RT device.

But we know that it can't work unless a lot of other things get changed
in the kernel.

> > > > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> > > > > index 78a79a6a..1ab24cc 100644
> > > > > --- a/arch/arm/Kconfig
> > > > > +++ b/arch/arm/Kconfig
> > > > > @@ -1853,6 +1853,20 @@ config EARLY_IOREMAP
> > > > > the same virtual memory range as kmap so all early mappings must
> > > > > be unapped before paging_init() is called.
> > > > >
> > > > > +config EFI
> > > > > + bool "UEFI runtime service support"
> > > > > + depends on OF && !CPU_BIG_ENDIAN
> > > >
> > > > What is the dependency on !CPU_BIG_ENDIAN?
> > >
> > > Mainly on code not being implemented to byte-reverse UCS strings.
> >
> > Why would you byte-reverse /strings/? They normally just come in
> > order of the characters, and UTF-16 strings are already defined
> > as being big-endian or marked by the BOM character.
>
> Well, then that bit might just work[tm].
>
> Although no other architectures supported by UEFI support big-endian,
> so to be honest, I don't want to have to be the first one to validate
> that in order to get the basic support into the kernel.

I think there was a project to run UEFI on PowerPC on some stage, though
I can't find any code now.

> Some of the data structures might need swizzling though...
> Again - if there is demand, this can be dealt with at a later date.

Ok.

Arnd


\
 
 \ /
  Last update: 2014-01-14 15:01    [W:0.062 / U:0.500 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site