Hi Johannes, My original Email address is blocked by the server of kernel.org, so I have to change an Email address. Please see my reply inline. >Hi, > >> Hi Johannes and Peter, sorry to bother but I have one question >> on this change. The do_ctors() won’t be executed for UML >> because *the constructors have already been called for ELF*. >> >> *__ctors_start* and *__ctors_end* symbols. See link: >> https://elixir.bootlin.com/linux/v5.12.2/source/include/asm-generic/vmlinux.lds.h#L676 >> >> In my environment, UML+GCC 10, I can't find __gcov_init executed >> before kernel starts. So I did some trace and found glibc >> __libc_csu_init >> will only execute constructors between *__init_array_start*and >> *__init_array_end*. >> Which means if do_ctors() is not executed for UML, no elsewhere will >> the constructors be executed. >> >> Shall we remove the *!defined(CONFIG_UML)* for GCC, or I just missed >> some steps to make the GCOV work for UML? > >No, that doesn't seem like the right solution. > >Perhaps then with that toolchain (or configuration thereof) we need to >provide __init_array_start/end labels? Yes, that's how I worked around in my local environment (change linker script to add _init_array_start/end labels). So the __gcov_init is called before start_kernel. > >Or ... maybe that actually just needs to be removed, so that the >toolchain gets to choose? > >Hmm. Pretty sure it worked for me, I think also with gcc 10, but not >sure exactly where I tested. I will make sure my environment is clean and try again. Could you please use gdb to check when __gcov_init is called in your setup? e.g. (1) gdb *your uml elf* (2) b __gcov_init (3) r (4) when the execution is breaked, use 'bt' to check the call stack Thanks Lambert > >johannes > > >
