> On 2023-07-14 17:47:23+0800, Zhangjin Wu wrote: > > > On 2023-07-14 13:58:13+0800, Zhangjin Wu wrote: > > > [..] > > > > I was also not able to reproduce the issue. > > > > > > > Thanks very much for your 'reproduce' result, It is so weird, just > > rechecked the toolchain, 13.1.0 from https://mirrors.edge.kernel.org/ is > > ok, gcc 9, gcc 10.3 not work. > > > > But even in the page of 13.1.0 [1], we still see this line: > > > > Most optimizations are completely disabled at -O0 or if an -O level is not set on the command line, even if individual optimization flags are specified. > > > > Not sure if "individual optimization flags" also means the optimize() > > flags in gcc attributes. or the doc is not updated yet? > > > > And further found gcc 11.1.0 is ok, gcc 10.4 still not work, so, gcc > > 11.1.0 may changed something to let the "individual optimization flags" > > work with -O0. > > > > We may need to at least document this issue in some files, -O0 is not such a > > frequently-used option, not sure if we still need -O0 work with the older gcc < > > 11.1.0 ;-) > > It seems we can avoid the issue by enforcing optimizations for _start: > > diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch-x86_64.h > index f5614a67f05a..b9d8b8861dc4 100644 > --- a/tools/include/nolibc/arch-x86_64.h > +++ b/tools/include/nolibc/arch-x86_64.h > @@ -161,12 +161,9 @@ > * 2) The deepest stack frame should be zero (the %rbp). > * > */ > -void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void) > +void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void) > Great, it works and it is minimal enough ;-) Thanks very much. > > > > Willy, I'm not sure if the issues solved by the commit 7f8548589661 > > ("tools/nolibc: make compiler and assembler agree on the section around > > _start") still exist after we using _start_c()? > > > > Thomas, because we plan to move the stackprotector init to _start_c(), If using > > pure assembly _start, we may also not need the __no_stack_protector macro too? > > It would probably not needed anymore in this case. > Yeah, but let's reserve it as-is for we have the working omit-frame-pointer now. Best regards, Zhangjin > Thomas
