Messages in this thread | | | From | Nick Desaulniers <> | Date | Mon, 22 May 2023 12:52:13 -0700 | Subject | Re: [PATCH v4] Makefile.compiler: replace cc-ifversion with compiler-specific macros |
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On Mon, May 22, 2023 at 9:52 AM Greg KH <gregkh@linuxfoundation.org> wrote: > > On Mon, May 22, 2023 at 12:09:34PM +0200, Ricardo Cañuelo wrote: > > On vie, may 19 2023 at 08:57:24, Nick Desaulniers <ndesaulniers@google.com> wrote: > > > It could be; if the link order was changed, it's possible that this > > > target may be hitting something along the lines of: > > > https://isocpp.org/wiki/faq/ctors#static-init-order i.e. the "static > > > initialization order fiasco" > > > > > > I'm struggling to think of how this appears in C codebases, but I > > > swear years ago I had a discussion with GKH (maybe?) about this. I > > > think I was playing with converting Kbuild to use Ninja rather than > > > Make; the resulting kernel image wouldn't boot because I had modified > > > the order the object files were linked in. If you were to randomly > > > shuffle the object files in the kernel, I recall some hazard that may > > > prevent boot. > > > > I thought that was specifically a C++ problem? But then again, the > > kernel docs explicitly say that the ordering of obj-y goals in kbuild is > > significant in some instances [1]: > > Yes, it matters, you can not change it. If you do, systems will break. > It is the only way we have of properly ordering our init calls within > the same "level".
Ah, right it was the initcall ordering. Thanks for the reminder.
(There's a joke in there similar to the use of regexes to solve a problem resulting in two new problems; initcalls have levels for ordering, but we still have (unexpressed) dependencies between calls of the same level; brittle!).
+Maksim, since that might be relevant info for the BOLT+Kernel work.
Ricardo, https://elinux.org/images/e/e8/2020_ELCE_initcalls_myjosserand.pdf mentions that there's a kernel command line param `initcall_debug`. Perhaps that can be used to see if 5750121ae7382ebac8d47ce6d68012d6cd1d7926 somehow changed initcall ordering, resulting in a config that cannot boot? -- Thanks, ~Nick Desaulniers
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