On 05/01/2013 07:18 AM, Tom Rini wrote: > On 04/30/2013 10:19 PM, Rusty Russell wrote: >> Tom Rini <trini@xxxxxx> writes: >>> On 04/28/2013 10:59 PM, Rusty Russell wrote: >>>> Tom Rini <trini@xxxxxx> writes: >>>> >>>>> Recent gcc's may place functions into the .text.unlikely section and we >>>>> need to check this section as well for section mismatches now otherwise >>>>> we may have false negatives for this test. >>>> >>>> Hmm, I don't think it's all that recent, is it? I can find it back to >>>> gcc 4.0.4: >>>> >>>> `-freorder-functions' >>>> Reorder functions in the object file in order to improve code >>>> locality. This is implemented by using special subsections >>>> `.text.hot' for most frequently executed functions and >>>> `.text.unlikely' for unlikely executed functions. Reordering is >>>> done by the linker so object file format must support named >>>> sections and linker must place them in a reasonable way. >>>> >>>> Also profile feedback must be available in to make this option >>>> effective. See `-fprofile-arcs' for details. >>>> >>>> Enabled at levels `-O2', `-O3', `-Os'. >>>> >>>> The comment is the same in in gcc 4.7. >>>> >>>> So is your real issue that this section is generated with >>>> -fprofile-arcs, or has something changed with gcc 4.8, or...? >>> >>> I've started seeing this with Linaro based 4.7 toolchains. I can go >>> back through their releases and see when it starts showing up there if >>> it helps. I didn't add .text.hot as I didn't have that section at all, >>> fwiw. >> >> Weird, did you turn on CONFIG_GCOV_KERNEL? AFAICT you shouldn't see >> this section without that. > > Nope, CONFIG_GCOV_KERNEL is off. Must be related to whatever flags the > Linaro folks set as default on -O2 (at least in their 2013.03 release), > after reading over one of the .o.cmd files in the build. > > Do you want me to re-word the commit message a bit or ? Thanks! I poked around, and every Linaro binary I can grab (2012.01 and gcc 4.6 to 2013.04 and gcc 4.8) has this behaviour. -- Tom -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
