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Re: Using linker script to mark .debug_frame allocatable


On Wed, Jul 29, 2009 at 09:11:09AM -0700, David Daney wrote:
>
> DWARF based .eh_frame sections don't really have any architecture-specific 
> things in them.  The register numbering conventions are not needed when 
> unwinding, only if you wanted to catch an exception and restore the 
> registers, which I don't think you do in the kernel.  I think the only 
> architecture-specific code you would need is something to find the first CFA 
> given the machine state at the unwind point.
>

Ah, OK then. In that case, -funwind-tables sounds exactly like what I
want. Thanks guys. The reason I got confused is because ARM has support
in the kernel for using the ARM unwind tables but the code looks
distinctly un-DWARF like. But as Daniel has already said, ARM is
special.

> I would compile the whole thing with -fasynchronous-unwind-tables or 
> -funwind-tables and use the resulting .eh_frame sections.  That is what they 
> are there for.  Trying to make .debug_frame into an allocatable section 
> seems hacky to me.
>

Yep, it definitely is a hack. Luckily now we have a better solution ;-)

> Good luck, it is something I have thought about doing myself.

Great, would you be wanting to look at MIPS support? There's a few
arch-specific parts that are needed. I'll CC you when I post the RFC
patch to lkml if you'd like?


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