* Pstore : Query on using ramoops driver for DDR
@ 2021-02-09 20:46 Mukesh Ojha
2021-02-09 21:02 ` Luck, Tony
0 siblings, 1 reply; 3+ messages in thread
From: Mukesh Ojha @ 2021-02-09 20:46 UTC (permalink / raw)
To: lkml; +Cc: keescook, Anton Vorontsov, tony.luck, ccross
Hi All,
Can we use existing backend pstore ram driver (fs/pstore/ram.c) for DDR
instead of SRAM ?
Was the current driver written only to support persistant RAM like SRAM
or it can accept further change
to support DDR, If we have a mechanism to copy stored data from DDR to
external device after the crash.
Thanks,
Mukesh
^ permalink raw reply [flat|nested] 3+ messages in thread
* RE: Pstore : Query on using ramoops driver for DDR
2021-02-09 20:46 Pstore : Query on using ramoops driver for DDR Mukesh Ojha
@ 2021-02-09 21:02 ` Luck, Tony
2021-02-10 15:33 ` Mukesh Ojha
0 siblings, 1 reply; 3+ messages in thread
From: Luck, Tony @ 2021-02-09 21:02 UTC (permalink / raw)
To: Mukesh Ojha, lkml; +Cc: keescook, Anton Vorontsov, ccross
> Can we use existing backend pstore ram driver (fs/pstore/ram.c) for DDR
> instead of SRAM ?
The expectation for pstore is that the system will go through a reset when it
crashes. Most systems do not preserve DDR contents across reset.
> Was the current driver written only to support persistant RAM like SRAM
> or it can accept further change
Linux is in a constant state of change :-)
> to support DDR, If we have a mechanism to copy stored data from DDR to
> external device after the crash.
See above about DDR contents. But if you have a platform that does preserve
DDR contents until your "mechanism" can copy the pstore buffer, then post
a patch.
-Tony
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Pstore : Query on using ramoops driver for DDR
2021-02-09 21:02 ` Luck, Tony
@ 2021-02-10 15:33 ` Mukesh Ojha
0 siblings, 0 replies; 3+ messages in thread
From: Mukesh Ojha @ 2021-02-10 15:33 UTC (permalink / raw)
To: Luck, Tony, lkml; +Cc: keescook, Anton Vorontsov, ccross
On 2/10/2021 2:32 AM, Luck, Tony wrote:
>> Can we use existing backend pstore ram driver (fs/pstore/ram.c) for DDR
>> instead of SRAM ?
> The expectation for pstore is that the system will go through a reset when it
> crashes. Most systems do not preserve DDR contents across reset.
>
> to support DDR, If we have a mechanism to copy stored data from DDR to
> external device after the crash.
>> Was the current driver written only to support persistant RAM like SRAM
>> or it can accept further change
> Linux is in a constant state of change :-)
>
> See above about DDR contents. But if you have a platform that does preserve
> DDR contents until your "mechanism" can copy the pstore buffer, then post
> a patch.
Thanks for the reply
I have posted the patch.
https://lore.kernel.org/patchwork/patch/1378949/
-Mukesh
>
> -Tony
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-02-09 20:46 Pstore : Query on using ramoops driver for DDR Mukesh Ojha
2021-02-09 21:02 ` Luck, Tony
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