linux-kernel - Re: asm-generic update candidates?

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Date:	Fri, 4 Sep 2009 15:32:50 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Robin Getz <rgetz@...ckfin.uclinux.org>
Cc:	Mike Frysinger <vapier.adi@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: asm-generic update candidates?

On Thursday 03 September 2009, Robin Getz wrote:
> Arnd:
> 
> I was reviewing some files in ./arch/blackfin/include for missing copyrights, 
> and while tracking things down I noticed there were still some likely 
> candidates for inclusion in asm-generic...

Ah, thanks. I basically started out with the list of files that exist in
almost all architectures. I never looked at files that are identical in
some architectures but nonexistent in more than a few others.

Also, my plan is to do one architecture at a time, not one file at a time
across all architectures, because that will reduce the need for coordination
between multiple maintainers.

> All seem to be the same file:
> 
> md5sum:
> 5b6b31d728ed2ed0df73c56676fdc68f  blackfin/include/asm/fb.h
> 5b6b31d728ed2ed0df73c56676fdc68f  cris/include/asm/fb.h
> 5b6b31d728ed2ed0df73c56676fdc68f  frv/include/asm/fb.h
> 5b6b31d728ed2ed0df73c56676fdc68f  h8300/include/asm/fb.h
> 5b6b31d728ed2ed0df73c56676fdc68f  s390/include/asm/fb.h
> 5b6b31d728ed2ed0df73c56676fdc68f  xtensa/include/asm/fb.h

Look at the latest version. Some architectures have already started
using the generic version, e.g. blackfin.

> e31d052cbba4f417ba2158a41b0d8709  arm/include/asm/fb.h
> e31d052cbba4f417ba2158a41b0d8709  m32r/include/asm/fb.h
> e31d052cbba4f417ba2158a41b0d8709  sh/include/asm/fb.h

Interesting one. The only difference between these and the
above is the use of pgprot_writecombine, which is defined as
pgprot_noncached on the other architectures.

> Mostly the same:
>  mn10300/include/asm/shmparam.h
>  frv/include/asm/shmparam.h
>  m68k/include/asm/shmparam.h
>  h8300/include/asm/shmparam.h
>  alpha/include/asm/shmparam.h
>  x86/include/asm/shmparam.h
>  m32r/include/asm/shmparam.h
>  avr32/include/asm/shmparam.h
>  powerpc/include/asm/shmparam.h
>  blackfin/include/asm/shmparam.h
> 
> All the same:
> frv/include/asm/ucontext.h
> h8300/include/asm/ucontext.h
> avr32/include/asm/ucontext.h
> m32r/include/asm/ucontext.h
> cris/include/asm/ucontext.h
> alpha/include/asm/ucontext.h
> mips/include/asm/ucontext.h
> microblaze/include/asm/ucontext.h
> mn10300/include/asm/ucontext.h
> blackfin/include/asm/ucontext.h

Yes, these should come naturally when the architectures
get changed to use the generic headers.

> There seems to be lots of similarities in
>  */include/asm/types.h
>  */include/asm/kmap_types.h
>  */include/asm/termios.h
>  */include/asm/socket.h
>  */include/asm/param.h
>  */include/asm/signal.h (but not all)
>  */include/asm/posix_types.h
>  */include/asm/termbits.h
>  */include/asm/segment.h
>  */include/asm/auxvec.h
>  */include/asm/shmbuf.h
>  */include/asm/spinlock_types.h
> 
> Do you keep a list somewhere?

Well, this is how I started out writing doing the common files
in the first place. I looked at the most similar files, and then
used vimdiff on up to four files at a time, changing them to
be exactly identical by editing out all the bitrot.

In general, if a file exists in asm-generic, it should be usable
by some of the architectures, if it does not exist then either it
is too hard to make a generic version or I have not looked at it
yet.

If you want to help convert an architecture, try doing

for i in include/asm-generic/*.h ; do
      vimdiff ${i} arch/${ARCH}/include/asm/${i##*/}
done

If the files are identical, replace the contents of the arch
specific one with a simple #include <asm-generic/${i}>. If they
are almost identical, add overrides like in
arch/microblaze/include/asm/posix_types.h, possibly adding the
option for overriding to the generic file. For files that
are rather different, just leave them alone.

	Arnd <><
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