Messages in this thread | | | Date | Tue, 9 Aug 2022 16:06:08 -0700 | From | Kees Cook <> | Subject | Re: Invalid pstore_blk use? |
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On Tue, Aug 09, 2022 at 11:35:08AM -0700, Florian Fainelli wrote: > Hi Kees, WeiXiong, > > On 7/14/22 20:49, Florian Fainelli wrote: > > Hi Kees, WeiXiong, > > > > I am trying to make use of pstore_blk which is BTW exactly what I had > > been looking for to store panic/console logs onto an eMMC partition. > > > > Using the 5.10 kernel plus: > > > > 7e2e92e9861b Revert "mark pstore-blk as broken" > > 01c28bc8f389 pstore/blk: Use the normal block device I/O path > > 2a7507999638 pstore/blk: remove {un,}register_pstore_blk > > fef0b337cd25 pstore/zone: cap the maximum device size > > > > or the android13-5.15 (at Merge 5.15.40 into android13-5.15) kernel with > > no changes and using: > > > > mount -t pstore pstore /sys/fs/pstore > > modprobe pstore_blk blkdev=/dev/mmcblk1p9 best_effort=yes > > > > upon triggering a crash with: > > > > echo c > /proc/sysrq-trigger > > > > and rebooting and remounting the pstore filesystem and loading > > pstore_blk, I only have: > > > > # ls /sys/fs/pstore/ > > console-pstore_blk-0 > > > > which contains the entire console log up to, but excluding the crash. > > The kernel does show that pstore_blk was used for all 3 types of kmsg, > > pmsg and console: > > > > [ 28.649514] pstore_zone: capping size to 128MiB > > [ 28.712894] pstore_zone: registered pstore_blk as backend for > > kmsg(Oops) pmsg console > > [ 28.721145] pstore: Using crash dump compression: deflate > > [ 28.906253] printk: console [pstore_blk-1] enabled > > [ 28.911229] pstore: Registered pstore_blk as persistent store backend > > [ 28.917735] pstore_blk: attached pstore_blk:/dev/mmcblk1p9 > > (134217728) (no dedicated panic_write!) > > > > there is no automatic reboot upon panic, so I just tend to reboot after > > 2-3 seconds manually. The kernel is configured with the default > > CONFIG_PSTORE_* options. > > > > Is the observed behavior a limitation of the best_effort mode? If so, do > > we have any plans to implementing a non-best effort mode for eMMC > > devices? > > Any feedback on my email? I did try to get kernel panics to be dumped out to
Hi! Sorry I lost this email originally. :)
> a dedicated /dev/mtdblock* partition for which there ought to be support for > mtd->panic_write, but it still did not work any better. Is there something
With the mtdblock driver, do you still see:
pstore_blk: attached pstore_blk:/dev/... (no dedicated panic_write!) ^^^^^^^^^^^^^^^^^^^^^^^^^
> obvious that I am missing which prevents kernel panics from being logged?
Unfortunately it really depends on how the drivers are built. If the block layer is shut down during a panic, pstore_blk won't catch the panic. :(
-- Kees Cook
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