Messages in this thread | | | Date | Wed, 11 Jan 2012 12:25:44 -0500 | From | Don Zickus <> | Subject | Re: [RFC][PATCH v4 -next 1/4] Move kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop() |
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On Wed, Jan 11, 2012 at 03:28:11PM +0800, Chen Gong wrote: > 于 2012/1/11 4:29, Seiji Aguchi 写道: > > > >>I agree with you. How about adding macros or something like WARN_ON(XX_ARCH) or > >>Kconfig to limit its scope? > > > >Thank you for giving me your idea. > >Your suggestions above will work for me because I'm a x86 user. > >If Tony agrees to it, I can update my patch. > > > >But, I'm hesitating to add WARN_ON() or change Kconfig only for specific arch > >because pstore aims for generic interface and this is related to its design. > >Also, ramoops is going to use pstore now. It doesn't depend on x86. > >I'm worried that ramoops users will complain about this change. > > > >So, I think a reasonable solution at this time is just adding some explanations > >about smp_send_stop() to documentation as follows. > > > >Users can use pstore with their own responsibility and ask developers > >if smp_send_stop() is reliable enough in panic situation on architecture they want to run. > > > >What do you think? > > > >--- > > Documentation/ABI/testing/pstore | 8 ++++++++ > > 1 files changed, 8 insertions(+), 0 deletions(-) > > > >diff --git a/Documentation/ABI/testing/pstore b/Documentation/ABI/testing/pstore > >index ff1df4e..5583729 100644 > >--- a/Documentation/ABI/testing/pstore > >+++ b/Documentation/ABI/testing/pstore > >@@ -11,6 +11,14 @@ Description: Generic interface to platform dependent persistent storage. > > of the console log is captured, but other interesting > > data can also be saved. > > > >+ In case of panic, pstore is invoked after smp_send_stop() > >+ ,a function call stopping other cpus, so that we can get > >+ logs simpler and cleaner with just one running cpu. > >+ > >+ As for x86, smp_send_stop() is reliable enough to work in > >+ panic situation. But we are not guaranteed that it works > >+ reliably on other architectures. > >+ > > # mount -t pstore -o kmsg_bytes=8000 - /dev/pstore > > > > $ ls -l /dev/pstore > > The explanation is great. but In my opinion, I still insist that > a WARN_ON() is necessary. What do you think, Tony and Don?
I guess I still don't understand why. Who uses kmsg_dump besides x86? It seems like there was only 3 or 4 subsystems that were registering.
Cheers, Don
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