Messages in this thread | | | Date | Thu, 5 Jul 2012 09:20:36 -0400 | From | Don Zickus <> | Subject | Re: [RFC][PATCH 0/2]efi_pstore: Avoid missing panic message in NVRAM |
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On Tue, Jul 03, 2012 at 11:33:57PM +0000, Seiji Aguchi wrote: > [Problem] > Current efi_pstore simply overwrites existing entries in NVRAM. > So, if 2nd panic happens before a user checks 1st panic message, 1st panic message will be lost.
I thought the rule was entries do not get overwritten until they are deleted first. Perhaps that is just an APEI thing, but it seems like that should be a good rule for EFI too.
Mainly because there is very little userspace apps that actually clear the old error records. So this could become a common problem.
Unless we are implementing a flight recorder option which explicitly states overwrite older entries?
Cheers, Don
> > [Solution] > To avoid missing 1st panic message, this patch introduce a rule checking if existing entries in NRAM are erasable to efi_pstore. > > [Patch Descriptions] > > [PATCH 1/2] Duplicate a shared code between write and erase callbacks > > Currently, efi_pstore driver shares a code erasing existing entries in NVRAM with write and erase callbacks. > But there some cases we should avoid erasing existing entries in write callback. (Please see PATCH 2/2). > This patch duplicates the code so that write and erase callbacks work independently. > > > [PATCH 2/2] write callback: Check if existing entry is erasable > > this patch introduce a rule checking if existing entries in NRAM are erasable to efi_pstore. > With this patch, if previous event is panic, efi_pstore never overwrite it. > > > drivers/firmware/efivars.c | 94 +++++++++++++++++++++++++++++++++++++++++++- > fs/pstore/platform.c | 4 +- > include/linux/pstore.h | 5 ++ > 3 files changed, 99 insertions(+), 4 deletions(-) > > Seiji
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