Top-level bits/ vs sysdeps/generic/bits/

[Zack Weinberg]

On 05/05/2016 12:15 AM, Mike Frysinger wrote:
> On 28 Apr 2016 21:39, Zack Weinberg wrote:
>> 1) There seem to be generic "bits" headers in a top-level directory
>> named bits/, as well as sysdeps/generic/bits/ which is where I would
>> expect them to be.  What's up with that?
> 
> i suspect it's something like:
> - bits/: The One True header that is used everywhere and overriding
>   doesn't make sense.
> - sysdeps/generic/bits/: We expect platforms to override it, so throw
>   it in here to signal as much.

Before revising this patch again I would like a definitive answer to
this question.

On further investigation, Roland moved sysdeps/generic/bits/ to bits/
_en masse_ in 2005:

2005-12-21  Roland McGrath  <roland@redhat.com>

        * sysdeps/generic/bits: Subdirectory and all files moved to ...
        * bits: ... here, new subdirectory.
        * Makeconfig (+includes): Reordered includes to put build and
        sysdeps dirs first after $(..)include, $(sysincludes) last.

I checked libc-alpha and libc-hacker for that month and there's no
mention of this change; there is, however, a closely related event where
Ulrich moved all the .c files out of sysdeps/generic to the appropriate
top-level module directories.  I'm guessing that the idea was eventually
to dispose of sysdeps/generic altogether (which I would certainly
support) and that there isn't supposed to be a sysdeps/generic/bits anymore.

Besides the file I added with the sysmacros.h patches, the only file
_currently_ in sysdeps/generic/bits is hwcap.h, which was added by
Richard Henderson in 2012:

commit c7683a6d02f3ed59f5cd119b3e8547f45a15912f
Author: Richard Henderson <rth@twiddle.net>
Date:   Sun May 20 10:34:00 2012 -0700

    Add <sys/auxv.h> and getauxval.

I'm also guessing that this was a simple oversight.

Roland and Richard cc:ed for comments.

zw

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