Re: [RFC PATCH v4 9/9] printk: use a new ringbuffer implementation

From: John Ogness
Date: Fri Aug 09 2019 - 03:08:38 EST

On 2019-08-09, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>> End result: a DRAM buffer can work, but is not "reliable".
>> Particularly if you turn power on and off, data retention of DRAM is
>> iffy. But it's possible, at least in theory.
>> So I have a patch that implements a "stupid ring buffer" for thisa
>> case, with absolutely zero data structures (because in the presense of
>> DRAM corruption, all you can get is "hopefully only slightly garbled
>> ASCII".
> Note that you can hook this into printk as a fake early serial device;
> just have the serial device write to the DRAM buffer.

Or the other way around, implement a fake console to handle writing the
messages (as they are being emitted from printk) to some special
area. Then the messages would even be pre-processed so that all
meta-data is already in ASCII form.

John Ogness