Re: Why do we include debug symbols in !maintainer_mode?
[Hyrum K Wright] > Although I don't know if this has any impact on the processor > i-cache, I still don't see much reason for using '-g -O2' in > non-maintainer mode. As others have said, no, it should have no effect on the icache, at least on systems I know (mainly ELF). The debug section isn't even loaded into memory at runtime, it's just sitting there eating disk until someone like gdb comes along and reads it explicitly. With my Linux distribution packager hat on, though, I wouldn't mind if the default were changed. I'd change it back so I could provide out-of-band debug symbols in my packages, but overriding CFLAGS at build time is so trivial that anyone doing any special handling like this shouldn't really be inconvenienced. -- Peter Samuelson | org-tld!p12n!peter | http://p12n.org/
Re: Why do we include debug symbols in !maintainer_mode?
Philip Martin writes: > Hyrum K Wright writes: > >> Although I don't know if this has any impact on the processor >> i-cache On a Linux system the debug symbols are in separate ELF sections, the loader probaby doesn't even map them into memory. -- Philip
Re: Why do we include debug symbols in !maintainer_mode?
On Thu, 2011-04-14 at 14:25 -0400, Philip Martin wrote: > I believe it is a GNU standard. Debug symbols can be used with an > optimised build although it is obviously easier to debug without > optimisation More specifically: stepping through a -g -O2 executable is pretty painful, but you can still usually get a decent stack trace from one.
Re: Why do we include debug symbols in !maintainer_mode?
Hyrum K Wright writes: > I just built a version of trunk to use on my "production" working > copies, and configured it without maintainer mode. I noticed that it > was using '-g -O2' in the CFLAGS, which seems completely nonsensical: > debug symbols often refer to stuff that gets optimized away, and just > bloats the final executable. Although I don't know if this has any > impact on the processor i-cache, I still don't see much reason for > using '-g -O2' in non-maintainer mode. > > Some voice in the back of my head says we've had this discussion > before, but I can't seem to find it. I just wanted to check here > before I went and changed things. (And for the record, I hacked my > local Makefile to remove '-g' from CFLAGS.) I believe it is a GNU standard. Debug symbols can be used with an optimised build although it is obviously easier to debug without optimisation Most distributions strip debug symbols from their binary packages automatically. These days GDB supports debug symbols in files separate from the executables, so some distributions have started shipping debug packages that contain the debug symbols for the stripped binaries. -- Philip
Why do we include debug symbols in !maintainer_mode?
I just built a version of trunk to use on my "production" working copies, and configured it without maintainer mode. I noticed that it was using '-g -O2' in the CFLAGS, which seems completely nonsensical: debug symbols often refer to stuff that gets optimized away, and just bloats the final executable. Although I don't know if this has any impact on the processor i-cache, I still don't see much reason for using '-g -O2' in non-maintainer mode. Some voice in the back of my head says we've had this discussion before, but I can't seem to find it. I just wanted to check here before I went and changed things. (And for the record, I hacked my local Makefile to remove '-g' from CFLAGS.) -Hyrum
