[RFC PATCH] drm.h: Fix DRM compilation with bare-metal toolchain.

[Nishanth Menon]

On 12:50-20130416, Arnd Bergmann wrote:
> On Tuesday 16 April 2013 12:48:28 Paul Sokolovsky wrote:
> > > diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> > > index 8d1e2bb..73a99e4 100644
> > > --- a/include/uapi/drm/drm.h
> > > +++ b/include/uapi/drm/drm.h
> > > @@ -36,7 +36,7 @@
> > >  #ifndef _DRM_H_
> > >  #define _DRM_H_
> > >  
> > > -#if defined(__linux__)
> > > +#if defined(__KERNEL__) || defined(__linux__)
> > >  
> > >  #include <linux/types.h>
> > >  #include <asm/ioctl.h>
> 
> This is still completely bogus, the __KERNEL__ symbol has no significance here.
> Either make the compiler define __linux__, or remove this #ifdef completely.
> 
Searching the v.39-rc7 tag, and greping for _linux_ a few interesting
list pops up. (pruned):
arch/arc/Makefile:cflags-y	+= -mA7 -fno-common -pipe -fno-builtin -D__linux__
arch/h8300/Makefile:KBUILD_CFLAGS += -D__linux__
arch/hexagon/Makefile:KBUILD_CFLAGS += -ffixed-$(TIR_NAME) -DTHREADINFO_REG=$(TIR_NAME) -D__linux__
arch/score/Makefile:	-D__linux__ -ffunction-sections -ffreestanding
arch/xtensa/Makefile:KBUILD_CFLAGS += -ffreestanding -D__linux__
^^ these architectures seem to bypass the pain entirely by defining
__linux__

arch/mips/include/uapi/asm/sgidefs.h:#ifndef __linux__
drivers/gpu/drm/radeon/radeon_cp.c:#ifdef __linux__
{snip}
drivers/scsi/aic7xxx/aic7770.c:#ifdef __linux__
drivers/scsi/aic7xxx/aic79xx.h:#ifndef __linux__
{snip}
drivers/scsi/aic7xxx/aic79xx_core.c:#ifdef __linux__
{snip}
drivers/scsi/aic7xxx/aic79xx_pci.c:#ifdef __linux__
drivers/scsi/aic7xxx/aic7xxx.h:#ifndef __linux__
drivers/scsi/aic7xxx/aic7xxx.h:#ifndef __linux__
drivers/scsi/aic7xxx/aic7xxx_93cx6.c:#ifdef __linux__
drivers/scsi/aic7xxx/aic7xxx_core.c:#ifdef __linux__
{snip}
drivers/scsi/aic7xxx/aic7xxx_pci.c:#ifdef __linux__
drivers/scsi/aic7xxx/aicasm/aicasm.h:#ifdef __linux__
drivers/scsi/aic7xxx/aicasm/aicasm_gram.y:#ifdef __linux__
drivers/scsi/aic7xxx/aicasm/aicasm_macro_scan.l:#ifdef __linux__
drivers/scsi/aic7xxx/aicasm/aicasm_scan.l:#ifdef __linux__
drivers/scsi/aic7xxx/aicasm/aicasm_symbol.c:#ifdef __linux__
drivers/scsi/aic7xxx/aicasm/aicasm_symbol.h:#ifdef __linux__
drivers/scsi/dpt/osd_defs.h:#if (defined(__linux__))
drivers/staging/ced1401/machine.h:#if (defined(__linux__) || defined(_linux) || defined(__linux)) && !defined(LINUX)
include/acpi/platform/acenv.h:#if defined(_LINUX) || defined(__linux__)
include/linux/coda.h:#if defined(__linux__)
include/uapi/drm/drm.h:#if defined(__linux__)
include/uapi/linux/coda.h:#if defined(__linux__)
include/uapi/linux/fuse.h:#ifdef __linux__

And then we have the following as well..
fs/ext4/ext4.h:#if defined(__KERNEL__) || defined(__linux__)

Trying out a few different prebuilt compilers I had around, I see:
http://pastebin.com/bTVDLTb1

So, is our approach just to use __linux__ for builds? I am trying to
understand rationale behind why #include <linux/types.h> #include <asm/ioctl.h>
would want __linux__ and why __KERNEL__ check is un-wanted.
Ofcourse, I cant comment about the "One of the BSDs" in else options..
and why we'd like to keep it around in kernel :)

-- 
Regards,
Nishanth Menon