Re: MIPS textrel fix

[David Daney <ddaney@avtrex.com>]

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.
> OK?
> 
> 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