Re: Invalid pstore_blk use?

[Kamal Dasu]

Kees,

Thanks for your reply. I will send the RFC patch.

Kamal

On Wed, Dec 7, 2022 at 5:13 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>
> On Fri, Nov 18, 2022 at 03:41:44PM -0500, Kamal Dasu wrote:
> > Kees,
> >
> > I am in the process of implementing  mmcpstore  backend for mmc  based
> > on the mtdpstore driver
> >
> > This is what is registered with register_pstore_device(&cxt->dev);
> > cxt->dev.flags = PSTORE_FLAGS_DMESG;
> > cxt->dev.zone.read = mmcpstore_read;
> > cxt->dev.zone.write = mmcpstore_write;
> > cxt->dev.zone.erase = mmcpstore_erase;
> > cxt->dev.zone.panic_write = mmcpstore_panic_write;
> >
> > # dmesg | grep pstor
> > [    0.000000] Kernel command line: pstore_blk.blkdev=/dev/mmcblk1p8
> > crash_kexec_post_notifiers printk.always_kmsg_dump
> > [    1.993986] pstore_zone: registered pstore_blk as backend for
> > kmsg(Oops,panic_write) pmsg
> > [    2.002582] pstore: Using crash dump compression: deflate
> > [    2.008133] pstore: Registered pstore_blk as persistent store backend
> > [    2.020907] mmcpstore: /dev/mmcblk1p8 size 131072 start sector
> > 34468 registered as psblk backend
> > [   17.868753] psz_kmsg_recover_meta: pstore_zone: no valid data in
> > kmsg dump zone 0
> > [   18.298933] psz_recover_zone: pstore_zone: no valid data in zone pmsg
> > [   18.305398] psz_recovery: pstore_zone: recover end!
> >
> > The driver is successfully registered and the read path works when
> > /sys/fs/pstor is mounted , however mmc_pstore_panic_write is not
> > called.
> > Need help in understanding what could be missing. I am using the
> > latest upstream kernel for testing.
>
> Hi!
>
> Can you send an RFC patch? I'd expect this to work as you've currently
> described it, but without code I'd just be guessing. :)
>
> -Kees
>
> --
> Kees Cook