Re: Mixing 32-bit and 64-bit DWARF2/3 sections

James E Wilson
2004-11-08T23:57:42Z

On Mon, 2004-11-08 at 15:37, Thiemo Seufer wrote:
> FWIW, I doubt going back unconditionally to a 32bit format is the right
> thing to do for a fully 64bit ABI. Applications tend to grow further,
> as does the accompanying debug info, so the 32bit limit comes closer.

DWARF2 debug info has a field to indicate pointer size, and uses this
for addresses. The only limit to DWARF2 debug info is that cross
references within the DWARF2 debug info are specified by 32-bit fields.
Thus, in order to exceed the 32-bit limit, one of the DWARF2 sections
must be larger than 4GB. Since the DWARF2 info is spread across
multiple sections, it would be possible to have 36GB of DWARF2 debug
info, and still not exceed the 32-bit limit, if none of the individual
sections are larger than 4GB. You can have a 1TB application, and still
not exceed the 32-bit limit, if none of the individual DWARF2 debug
section are larger than 4GB.

I don't think we should be worried about use of 32-bit DWARF2 debug
info. We are unlikely to hit the limits anytime soon. And if we do hit
the limits, then we will likely have other more serious problems.
--
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com