Re: [PATCH v2 1/1] kexec: dump kmessage before machine_kexec
On Thu, Jan 28, 2021 at 3:01 PM Eric W. Biederman wrote: > > Pavel Tatashin writes: > > > kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before > > machine_restart(), machine_halt(), machine_power_off(), the only one that > > is missing is machine_kexec(). > > > > The dmesg output that it contains can be used to study the shutdown > > performance of both kernel and systemd during kexec reboot. > > > > Here is example of dmesg data collected after kexec: > > As long was we keep kmsg_dump out of the crash_kexec path where > it completely breaks kexec on panic this seems a reasonable thing to do. > On the ordinary kernel_kexec path everything is expected to be working. This is an ordinary kexec reboot path, not kdump. > > Is kmsg_dump expected to work after all of the device drivers > are shut down? Otherwise this placement of kmsg_dump is too late. Yes it is. It is called after device_shutdown(); in all other places. Thank you, Pasha
Re: [PATCH v2 1/1] kexec: dump kmessage before machine_kexec
Pavel Tatashin writes: > kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before > machine_restart(), machine_halt(), machine_power_off(), the only one that > is missing is machine_kexec(). > > The dmesg output that it contains can be used to study the shutdown > performance of both kernel and systemd during kexec reboot. > > Here is example of dmesg data collected after kexec: As long was we keep kmsg_dump out of the crash_kexec path where it completely breaks kexec on panic this seems a reasonable thing to do. On the ordinary kernel_kexec path everything is expected to be working. Is kmsg_dump expected to work after all of the device drivers are shut down? Otherwise this placement of kmsg_dump is too late. Eric > root@dplat-cp22:~# cat /sys/fs/pstore/dmesg-ramoops-0 | tail > ... > <6>[ 70.914592] psci: CPU3 killed (polled 0 ms) > <5>[ 70.915705] CPU4: shutdown > <6>[ 70.916643] psci: CPU4 killed (polled 4 ms) > <5>[ 70.917715] CPU5: shutdown > <6>[ 70.918725] psci: CPU5 killed (polled 0 ms) > <5>[ 70.919704] CPU6: shutdown > <6>[ 70.920726] psci: CPU6 killed (polled 4 ms) > <5>[ 70.921642] CPU7: shutdown > <6>[ 70.922650] psci: CPU7 killed (polled 0 ms) > > Signed-off-by: Pavel Tatashin > Reviewed-by: Kees Cook > Reviewed-by: Petr Mladek > Reviewed-by: Bhupesh Sharma > --- > kernel/kexec_core.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c > index 4f8efc278aa7..e253c8b59145 100644 > --- a/kernel/kexec_core.c > +++ b/kernel/kexec_core.c > @@ -37,6 +37,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -1180,6 +1181,7 @@ int kernel_kexec(void) > machine_shutdown(); > } > > + kmsg_dump(KMSG_DUMP_SHUTDOWN); > machine_kexec(kexec_image); > > #ifdef CONFIG_KEXEC_JUMP
Re: [PATCH v2 1/1] kexec: dump kmessage before machine_kexec
On 01/26/21 at 03:41pm, Pavel Tatashin wrote: > kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before > machine_restart(), machine_halt(), machine_power_off(), the only one that > is missing is machine_kexec(). > > The dmesg output that it contains can be used to study the shutdown > performance of both kernel and systemd during kexec reboot. > > Here is example of dmesg data collected after kexec: > > root@dplat-cp22:~# cat /sys/fs/pstore/dmesg-ramoops-0 | tail > ... > <6>[ 70.914592] psci: CPU3 killed (polled 0 ms) > <5>[ 70.915705] CPU4: shutdown > <6>[ 70.916643] psci: CPU4 killed (polled 4 ms) > <5>[ 70.917715] CPU5: shutdown > <6>[ 70.918725] psci: CPU5 killed (polled 0 ms) > <5>[ 70.919704] CPU6: shutdown > <6>[ 70.920726] psci: CPU6 killed (polled 4 ms) > <5>[ 70.921642] CPU7: shutdown > <6>[ 70.922650] psci: CPU7 killed (polled 0 ms) > > Signed-off-by: Pavel Tatashin > Reviewed-by: Kees Cook > Reviewed-by: Petr Mladek > Reviewed-by: Bhupesh Sharma > --- > kernel/kexec_core.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c > index 4f8efc278aa7..e253c8b59145 100644 > --- a/kernel/kexec_core.c > +++ b/kernel/kexec_core.c > @@ -37,6 +37,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -1180,6 +1181,7 @@ int kernel_kexec(void) > machine_shutdown(); > } > > + kmsg_dump(KMSG_DUMP_SHUTDOWN); > machine_kexec(kexec_image); Looks good to me, thx. Acked-by: Baoquan He > > #ifdef CONFIG_KEXEC_JUMP > -- > 2.25.1 > > > ___ > kexec mailing list > ke...@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec >
[PATCH v2 1/1] kexec: dump kmessage before machine_kexec
kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before machine_restart(), machine_halt(), machine_power_off(), the only one that is missing is machine_kexec(). The dmesg output that it contains can be used to study the shutdown performance of both kernel and systemd during kexec reboot. Here is example of dmesg data collected after kexec: root@dplat-cp22:~# cat /sys/fs/pstore/dmesg-ramoops-0 | tail ... <6>[ 70.914592] psci: CPU3 killed (polled 0 ms) <5>[ 70.915705] CPU4: shutdown <6>[ 70.916643] psci: CPU4 killed (polled 4 ms) <5>[ 70.917715] CPU5: shutdown <6>[ 70.918725] psci: CPU5 killed (polled 0 ms) <5>[ 70.919704] CPU6: shutdown <6>[ 70.920726] psci: CPU6 killed (polled 4 ms) <5>[ 70.921642] CPU7: shutdown <6>[ 70.922650] psci: CPU7 killed (polled 0 ms) Signed-off-by: Pavel Tatashin Reviewed-by: Kees Cook Reviewed-by: Petr Mladek Reviewed-by: Bhupesh Sharma --- kernel/kexec_core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 4f8efc278aa7..e253c8b59145 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -37,6 +37,7 @@ #include #include #include +#include #include #include @@ -1180,6 +1181,7 @@ int kernel_kexec(void) machine_shutdown(); } + kmsg_dump(KMSG_DUMP_SHUTDOWN); machine_kexec(kexec_image); #ifdef CONFIG_KEXEC_JUMP -- 2.25.1
