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) > > 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. Thomas
