Re: [POC][RFC][PATCH 0/2] pstore/mm/x86: Add wildcard memmap to map pstore consistently

Joel Fernandes
2024-04-09T22:41:19Z

> On Apr 10, 2024, at 3:55 AM, Luck, Tony <tony.luck@intel.com> wrote:
>
> ﻿
>>
>>> I forgot to mention that this makes it trivial for any machine that doesn't
>>> clear memory on soft-reboot, to enable console ramoops (to have access to
>>> the last boot dmesg without needing serial).
>>>
>>> I tested this on a couple of my test boxes and on QEMU, and it works rather
>>> well.
>>
>> I've long wanted a "stable for this machine and kernel" memory region
>> like this for pstore. It would make testing much easier.
>
> Which systems does this work on? I'd assume that servers (and anything
> else with ECC memory) would nuke contents while resetting ECC to clean
> state.

If that were the case universally, then ramoops pstore backend would not work either?

And yet we get the last kernel logs via the pstore for many years now, on embedded-ish devices.

From my reading, ECC-enabled DRAM is not present on lots of systems and IIRC, pstore ramoops has its own ECC.

Or did I miss a recent trend with ECC-enabled DRAM?

- Joel

>
> -Tony