On Fri, Sep 8, 2023 at 2:52 PM Ricardo Ribalda <ribalda@xxxxxxxxxxxx> wrote: > > Hi Song > > On Fri, 8 Sept 2023 at 23:48, Song Liu <song@xxxxxxxxxx> wrote: > > > > Hi Ricardo, > > > > Thanks for your kind reply. > > > > On Fri, Sep 8, 2023 at 2:18 PM Ricardo Ribalda <ribalda@xxxxxxxxxxxx> wrote: > > > > > > Hi Song > > > > > > On Fri, 8 Sept 2023 at 01:08, Song Liu <song@xxxxxxxxxx> wrote: > > > > > > > > Hi Ricardo and folks, > > > > > > > > On Fri, May 19, 2023 at 7:48 AM Ricardo Ribalda <ribalda@xxxxxxxxxxxx> wrote: > > > > > > > > > > When upreving llvm I realised that kexec stopped working on my test > > > > > platform. > > > > > > > > > > The reason seems to be that due to PGO there are multiple .text sections > > > > > on the purgatory, and kexec does not supports that. > > > > > > > > > > Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> > > > > > > > > We are seeing WARNINGs like the following while kexec'ing a PGO and > > > > LTO enabled kernel: > > > > > > > > WARNING: CPU: 26 PID: 110894 at kernel/kexec_file.c:919 > > > > kexec_load_purgatory+0x37f/0x390 > > > > > > > > AFAICT, the warning was added by this set, and it was triggered when > > > > we have many .text sections > > > > in purgatory.ro. The kexec was actually successful. So I wonder > > > > whether we really need the > > > > WARNING here. If we disable LTO (PGO is still enabled), we don't see > > > > the WARNING any more. > > > > > > > > I also tested an older kernel (5.19 based), where we also see many > > > > .text sections with LTO. It > > > > kexec()'ed fine. (It doesn't have the WARN_ON() in > > > > kexec_purgatory_setup_sechdrs). > > > > > > You have been "lucky" that the code has chosen the correct start > > > address, you need to modify the linker script of your kernel to > > > disable PGO. > > > You need to backport a patch like this: > > > https://lore.kernel.org/lkml/CAPhsuW5_qAvV0N3o+hOiAnb1=buJ1pLzqYW9D+Bwft6hxJvAeQ@xxxxxxxxxxxxxx/T/#md68b7f832216b0c56bbec0c9b07332e180b9ba2b > > > > We already have this commit in our branch. AFAICT, the issue was > > triggered by LTO. So something like the following seems fixes it > > (I haven't finished the end-to-end test yet). Does this change make > > sense to you? > > if the end-to-end works, please send it as a patch to the mailing list. > > Thanks! :) OK, it works (AFAICT). Sending the patch. Thanks, Song
