On Sat, Aug 14, 2010 at 3:40 AM, Stefan Reinauer <[email protected]> wrote: > On 8/12/10 9:27 PM, Patrick Georgi wrote: >> 1. _bogus = ASSERT((SIZEOF(.bss) + SIZEOF(.data)) == 0, "Do not use >> global variables in romstage"); >> >> This one looks for the size of .bss and .data (initialized and >> uninitialized globals) and breaks the build if it finds any. It doesn't >> tell, which global variables are involved. >> >> >> 2. Add .bss and .data to /DISCARD/. >> >> That way, the linker complains about "missing" symbols (as they were >> discarded), but only if they were used by any surviving code. This >> means, it's no problem that the global is defined. If you use it >> later-on, it "mysteriously" breaks. The error message is rather cryptic, >> too: >> `variable' referenced in section `.rom.text' of >> coreboot-builds/kontron_986lcd-m/mainboard/kontron/986lcd-m/crt0.initobj.o: >> defined in discarded section >> `.data' of >> coreboot-builds/kontron_986lcd-m/mainboard/kontron/986lcd-m/crt0.initobj.o >> collect2: ld returned 1 exit status >> >> >> I tend to prefer the first option, but it doesn't give _any_ clues which >> variable is responsible (except for "look for globals"), but at least it >> does tell the user what the real problem is. > > I prefer option one, too, as > - it catches all global variables, not just the used ones. We want to be > sure that no such code sneaks in even if it's not used. > - it provides a clear error message on what is wrong, inszead of the > more cryptic one saying that a variable is defined in a discarded section.
I agree too. The problem was that a global variable was added unintentionally. Once the problem is indicated, it isn't hard to find the offending code. Marc -- http://se-eng.com -- coreboot mailing list: [email protected] http://www.coreboot.org/mailman/listinfo/coreboot
