Hi, Le dimanche 14 août 2016 à 13:31 +0200, Greg KH a écrit : > On Sun, Aug 14, 2016 at 07:11:01PM +0800, Hao Lee wrote: > > > > > > > > Just out of curiosity - is there a technical reason why -O0 > > > couldn't be used in Linux kernel? I don't know, spinlocks would > > > not work in this case because it's how GCC was written or > > > something. Or just nobody compiles and tests kernel like this so > > > it most likely would not work? > > > [...] > > Hi, I also like figuring out what's happening in the OS underlying. > > So I have some ideas about reducing optimization. Although you > > couldn't turn off optimization completely, you can use both -O2 and > > other options to reducing optimization as far as possible. > > You can use -O2 -Q -v to find out which options are enabled when > > using -O2. Then you can try -O2 -fno-defer-pop -fno-thread-jumps > > etc. to disable some options. I once used this approach to debug > > kernel-2.4 in bochs simulator. Unfortunately, this approach could > > not counteract the effects of -O2 completely, but it's worth a try. > > No, please don't do that. If you do, you will end up with a > completly unsuported and unknown system and no one will be able to > help you out with any sort of problem solving. > And what about -Og which is a dedicated optimization level since GCC 4.8 https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-Og-723 https://gcc.gnu.org/gcc-4.8/changes.html Regards. -- Yann Droneaud OPTEYA _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
