Re: [PATCH] efi: Work around ia64 build problem with ESRT driver.

[Mark Salter <msalter@redhat.com>]

On Mon, 2015-06-08 at 11:09 +0100, Matt Fleming wrote:
> On Fri, 05 Jun, at 03:14:54PM, Peter Jones wrote:
> > So, I'm told this problem exists in the world:
> > ----------------------------------------------
> > Subject: Build error in -next due to 'efi: Add esrt support'
> > 
> > Building ia64:defconfig ... failed
> > --------------
> > Error log:
> > 
> > drivers/firmware/efi/esrt.c:28:31: fatal error: asm/early_ioremap.h: No
> > such file or directory
> > ----------------------------------------------
> > 
> > I'm not really sure how it's okay that we have things in asm-generic on
> > some platforms but not others - is having it the same everywhere not the
> > whole point of asm-generic?
> > 
> > That said, ia64 doesn't have early-ioremap.h .  So instead, since it's
> > difficult to imagine new IA64 machines with UEFI 2.5, just don't build
> > this code there.
> > 
> > To me this looks like a workaround - doing something like:
> > 
> > generic-y += early_ioremap.h
> > 
> > in arch/ia64/include/asm/Kbuild would appear to be more correct, but
> > ia64 has its own early_memremap() decl in arch/ia64/include/asm/io.h ,
> > and it's a macro.  So adding the above /and/ requiring that asm/io.h be
> > included /after/ asm/early_ioremap.h in all cases would fix it, but
> > that's pretty ugly as well.  Since I'm not going to spend the rest of my
> > life rectifying ia64 headers vs "generic" headers that aren't generic,
> > it's much simpler to just not build there.
> > 
> > Note that I've only actually tried to build this patch on x86_64, but
> > esrt.o still gets built there, and that would seem to demonstrate that
> > the conditional building is working correctly at all the places the code
> > built before.  I no longer have any ia64 machines handy to test that the
> > exclusion actually works there.
> > 
> > Signed-off-by: Peter Jones <pjones@redhat.com>
> > Acked-by: Tony Luck <tony.luck@intel.com>
> > ---
> >  drivers/firmware/efi/Kconfig  | 5 +++++
> >  drivers/firmware/efi/Makefile | 3 ++-
> >  include/linux/efi.h           | 4 ++++
> >  3 files changed, 11 insertions(+), 1 deletion(-)
>  
> Thanks Peter, I picked this up with everyone's Ack/Test tags.
> 
> But now let's Cc some more people that can answer the questions you
> posed above, which would be the people mentioned in commit 9e5c33d7aeee
> ("mm: create generic early_ioremap() support").
> 
> Folks, is it legitimate to have headers in include/asm-generic/ that
> aren't available to all architectures? The build failure incurred by
> directly including asm/early_ioremap.h is noted above.

To answer generally, yes it is legitimate to have asm-generic headers
which are not used by all architectures.

The intent of asm-generic/fixmap.h was to consolidate the generic
bits copied by all architectures *which implemented fixmap.h* in
<arch>/include/asm. Not all architecture need to involve page
table mappings for fixmap-like support and fixmap makes no sense for
!MMU arches.

> 
> > diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
> > index 8de4da5..54071c1 100644
> > --- a/drivers/firmware/efi/Kconfig
> > +++ b/drivers/firmware/efi/Kconfig
> > @@ -18,6 +18,11 @@ config EFI_VARS
> >  	  Subsequent efibootmgr releases may be found at:
> >  	  <http://github.com/vathpela/efibootmgr>
> >  
> > +config EFI_ESRT
> > +	bool
> > +	depends on EFI && !IA64
> > +	default y
> > +
> >  config EFI_VARS_PSTORE
> >  	tristate "Register efivars backend for pstore"
> >  	depends on EFI_VARS && PSTORE
> > diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
> > index 26eabbc..6fd3da9 100644
> > --- a/drivers/firmware/efi/Makefile
> > +++ b/drivers/firmware/efi/Makefile
> > @@ -1,8 +1,9 @@
> >  #
> >  # Makefile for linux kernel
> >  #
> > -obj-$(CONFIG_EFI)			+= efi.o esrt.o vars.o reboot.o
> > +obj-$(CONFIG_EFI)			+= efi.o vars.o reboot.o
> >  obj-$(CONFIG_EFI_VARS)			+= efivars.o
> > +obj-$(CONFIG_EFI_ESRT)			+= esrt.o
> >  obj-$(CONFIG_EFI_VARS_PSTORE)		+= efi-pstore.o
> >  obj-$(CONFIG_UEFI_CPER)			+= cper.o
> >  obj-$(CONFIG_EFI_RUNTIME_MAP)		+= runtime-map.o
> > diff --git a/include/linux/efi.h b/include/linux/efi.h
> > index 024c27e..2092965 100644
> > --- a/include/linux/efi.h
> > +++ b/include/linux/efi.h
> > @@ -879,7 +879,11 @@ static inline efi_status_t efi_query_variable_store(u32 attributes, unsigned lon
> >  #endif
> >  extern void __iomem *efi_lookup_mapped_addr(u64 phys_addr);
> >  extern int efi_config_init(efi_config_table_type_t *arch_tables);
> > +#ifdef CONFIG_EFI_ESRT
> >  extern void __init efi_esrt_init(void);
> > +#else
> > +static inline void efi_esrt_init(void) { }
> > +#endif
> >  extern int efi_config_parse_tables(void *config_tables, int count, int sz,
> >  				   efi_config_table_type_t *arch_tables);
> >  extern u64 efi_get_iobase (void);
> > -- 
> > 2.4.2
> > 
>