Re: [PATCH 3/8] arch: uapi: asm: mman.h: Let MADV_FREE have same value for all architectures

[Minchan Kim]

On Sun, Nov 01, 2015 at 04:08:27PM -0800, Hugh Dickins wrote:
> On Fri, 30 Oct 2015, Minchan Kim wrote:
> > From: Chen Gang <gang.chen.5i5j@xxxxxxxxx>
> > 
> > For uapi, need try to let all macros have same value, and MADV_FREE is
> > added into main branch recently, so need redefine MADV_FREE for it.
> > 
> > At present, '8' can be shared with all architectures, so redefine it to
> > '8'.
> > 
> > Cc: rth@xxxxxxxxxxx <rth@xxxxxxxxxxx>,
> > Cc: ink@xxxxxxxxxxxxxxxxxxxx <ink@xxxxxxxxxxxxxxxxxxxx>
> > Cc: mattst88@xxxxxxxxx <mattst88@xxxxxxxxx>
> > Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> > Cc: jejb@xxxxxxxxxxxxxxxx <jejb@xxxxxxxxxxxxxxxx>
> > Cc: deller@xxxxxx <deller@xxxxxx>
> > Cc: chris@xxxxxxxxxx <chris@xxxxxxxxxx>
> > Cc: jcmvbkbc@xxxxxxxxx <jcmvbkbc@xxxxxxxxx>
> > Cc: Arnd Bergmann <arnd@xxxxxxxx>
> > Cc: linux-arch@xxxxxxxxxxxxxxx
> > Cc: linux-api@xxxxxxxxxxxxxxx
> > Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
> > Signed-off-by: Chen Gang <gang.chen.5i5j@xxxxxxxxx>
> 
> Let me add
> Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
> to this one too.
> 
> But I have extended your mail's Cc list: Darrick pointed out earlier
> that dietlibc has a Solaris #define MADV_FREE 0x5 in its mman.h,
> and that was in the kernel's sparc mman.h up until 2.6.25.  I doubt
> that presents any obstacle nowadays, but Dave Miller should be Cc'ed.
> 
> I was a little suspicious that 8 is available for MADV_FREE: why did
> the common/generic parameters start at 9 instead of 8 back in 2.6.16?
> I think the answer is that we had MADV_REMOVE coming in from one
> direction, and MADV_DONTFORK coming from another direction, and when
> Roland looked for where to start the commons for MADV_DONTFORK, it
> appeared that 8 was occupied - by MADV_REMOVE; then a little later
> MADV_REMOVE was shifted to become the first of the commons, at 9.

Thanks for Ack, Ccing relevant people and history!
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