On Monday 13 January 2014, Leif Lindholm wrote:
> On Mon, Jan 13, 2014 at 07:43:09PM +0100, Arnd Bergmann wrote:
> > > This patch implements basic support for UEFI runtime services in the
> > > ARM architecture - a requirement for using efibootmgr to read and update
> > > the system boot configuration.
> > >
> > > 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.
> > > 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.
> > We try hard to have
> > all kernel code support both big-endian and little-endian, and
> > I'm guessing there is a significant overlap between the people
> > that want UEFI support and those that want big-endian kernels.
>
> Not really. There might be some. Also, it is not necessarily the case
> that those people want to run the big-endian kernel at EL2.
>
> If a need is seen, this support can be added at a later date.
Ok.
> > > +struct efi_memory_map memmap;
> >
> > "memmap" is not a good name for a global identifier, particularly because
> > it's easily confused with the well-known "mem_map" array. This
> > wants namespace prefix like you other variable, or a "static" tag,
> > preferably both.
>
> It is defined by include/linux/efi.h.
This seems to be a mistake: there is no user of this variable outside
of arch/x86/platform/efi/efi.c and arch/x86/platform/efi/efi_64.c.
I think it should just be moved into an x86 specific header file,
or preferably be renamed in the process. There is also efi->memmap,
which seems to be the same pointer.
Note that a number of drivers have local memmap variables.
Arnd
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