Re: [PATCH v3 0/3] Add support for compiling with -ffunction-sections-fdata-sections

[Tim Abbott]

On Fri, 24 Apr 2009, Masami Hiramatsu wrote:

> What would you think about posting these patches plus -ffunction-sections/
> -fdata-sections patch to -mm tree, -tip tree, or -next tree as
> "playable" Ksplice patchset?

The section rename patch often merge conflicts with other changes.  I 
think that having it sit out in one of those trees for another release 
would result in a lot of unnecessary work rebasing patches between that 
tree and Linus' tree.

Once these -ffunction-sections support patches are merged, I intend to 
post the rest of the Ksplice patchset for one of those trees.

> If there are actual problems on those arch, I think you'd better post
> these patches as bugfixes with bug reports.

These problems are all discussed in the commit messages of the relevant 
patches.

One patch fixes modposting a kernel with more than 65536 ELF sections.  
It is certainly possible to get this many with allyesconfig and 
-ffunction-sections -fdata-sections.

Another fixes the issue that when you build with -ffunction-sections, 
modpost will print a large number of spurious warnings when it sees 
sections like .rodata.__func__.12345 which are generated by the __FUNC__ 
macro.

The patch with many scattered changes fixes the problem that with 
-ffunction-sections -fdata-sections, a function named head gets put in the 
".text.head" section, and your "static int percpu" ends up in the 
".data.percpu" section and probably ends up being made percpu.  This is a 
potentially nasty problem.

	-Tim Abbott
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