locale files and page size

["Joseph S. Myers" <joseph at codesourcery dot com>]

In <https://sourceware.org/ml/libc-alpha/2013-09/msg00109.html> I noted 
two sources of architecture-dependence of locale files: endianness and 
int32_t alignment.

I'd still welcome comments in reply to that message about the second of 
those issues - whether localedef should get an option to specify this 
alignment, for generating locales for other systems, or whether this 
architecture-dependence should be removed.  However, I've now found a 
third source of architecture-dependence.

The locarchive.c code aligns some locale data in the archive file to page 
boundaries, where pages are determined by getpagesize on the system 
running localedef.  This makes the archive (but not the separate locale 
files, if use of the archive is disabled) depend on the page size of the 
system running localedef - which is not only architecture-dependent, but 
may also vary among systems with the same architecture.

Now, I think this alignment is just some sort of optimization, so 
differences in page size don't affect the functionality of the binary 
locale data if used on a system with a different page size.  However, if 
the optimization makes sense at all, then when generating locales for a 
different system the appropriate page size for that system should be used.  
Furthermore, with interest recently in making builds of GNU/Linux 
distributions produce independently reproducible binaries, there should be 
a way to eliminate any such dependence on the system on which localedef 
was run.

So: should we simply eliminate this page-alignment optimization completely 
(I rather doubt it makes any significant difference to the cost of loading 
a locale from the archive) - or should it change to use an 
architecture-independent constant instead of calling getpagesize - or 
should it use an architecture-dependent constant (sufficient for the 
reproducible builds issue) together with a command-line option to change 
the assumed page size for the cross-build case - or should the default 
continue to be as at present, but with such a command-line option for both 
the cross-build and reproducible-build cases?

-- 
Joseph S. Myers
joseph@codesourcery.com