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Re: MIPS textrel fix

Daniel Jacobowitz wrote:
While stuck offline earlier today, I revisited the textrel-1 MIPS
failure.  Eric originally tried setting DF_TEXTREL during section
relocation, but it's too late: we add the entry in size_dynamic_sections.
But I couldn't see any other way to get it right, since there's no
hook to predict whether elf-eh-frame.c will eliminate a relocation.

The easiest approach I found was to annul the DT_TEXTREL and DT_FLAGS
changes in finish_dynamic_sections if no text relocations were
actually generated.  This is not immensely pretty, but does work.

For background, the problem arises from the use of absolute addresses
in .eh_frame.  In this case, they're being produced by gas CFI
directives.  Is there a reason we can't mix and match encodings?
i.e. why not have gas use a PC-relative format?  I'm sure there's
a reason, but I can't think of it...

Could it be related to the reason that GCC no longer generates a PC-relative .eh_frame?

I never fully understood the reason, but I think it has to do with MIPS-ELF specifications not allowing the needed relocation types (even though they work well in binutils/glibc/linux).

David Daney

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