Dear Linux folks,
On a Dell OptiPlex 5040 with Linux 5.3-rc8, I’ll try to get
efi-pstore working.
```
$ lsmod | grep efi
efi_pstore 16384 0
pstore 28672 1 efi_pstore
efivarfs 16384 1
$ dmesg | grep pstore
[ 2569.826541] pstore: Using crash dump compression: deflate
[ 2569.826542] pstore: Registered efi as persistent store backend
```
Triggering a crash with `echo c | sudo tee /proc/sysrq-trigger`,
there is nothing in `/sys/fs/pstore` after the reboot.
Please note, that there is also a crash kernel configured, so
there are actually to reboots, but that should not conflict,
right?
Hints on how to debug that would be appreciated. Please find the
Linux messages attached.
Kind regards,
Paul
On Thu, Sep 12, 2019 at 02:51:53PM +0200, Paul Menzel wrote:
> On a Dell OptiPlex 5040 with Linux 5.3-rc8, I’ll try to get
> efi-pstore working.
>
> ```
> $ lsmod | grep efi
> efi_pstore 16384 0
> pstore 28672 1 efi_pstore
> efivarfs 16384 1
> $ dmesg | grep pstore
> [ 2569.826541] pstore: Using crash dump compression: deflate
> [ 2569.826542] pstore: Registered efi as persistent store backend
> ```
>
> Triggering a crash with `echo c | sudo tee /proc/sysrq-trigger`,
> there is nothing in `/sys/fs/pstore` after the reboot.
>
> Please note, that there is also a crash kernel configured, so
> there are actually to reboots, but that should not conflict,
> right?
As long as the crash kernel doesn't delete all the EFI stored variables,
I would expect them to survive.
> Hints on how to debug that would be appreciated. Please find the
> Linux messages attached.
Things seem correct, though I've only done EFI testing under QEMU...
do other things, like BUG (rather than a full panic()) get recorded?
(Maybe try with the lkdtm module?) There was another recent issue with
the "c" sysrq[1] but that seemed to be Xen-specific.
[1] https://lore.kernel.org/lkml/[email protected]/
--
Kees Cook