Messages in this thread | | | Date | Tue, 23 May 2023 15:57:06 +0530 | Subject | Re: [PATCH v4] Makefile.compiler: replace cc-ifversion with compiler-specific macros | From | Shreeya Patel <> |
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Hi Nick and Masahiro,
On 23/05/23 01:22, Nick Desaulniers wrote: > 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?
Here are the links to Lava jobs ran with initcall_debug added to the kernel command line.
1. Where regression happens (5750121ae7382ebac8d47ce6d68012d6cd1d7926) https://lava.collabora.dev/scheduler/job/10417706 <https://lava.collabora.dev/scheduler/job/10417706>
2. With a revert of the commit 5750121ae7382ebac8d47ce6d68012d6cd1d7926 https://lava.collabora.dev/scheduler/job/10418012 <https://lava.collabora.dev/scheduler/job/10418012>
Thanks, Shreeya Patel
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