Hi, On 26-Sep-24 7:01 PM, Steven Rostedt wrote: > From: Steven Rostedt <[email protected]> > > At the 2024 Linux Plumbers Conference, I was talking with Hans de Goede > about the persistent buffer to display traces from previous boots. He > mentioned that UEFI can clear memory. In my own tests I have not seen > this. He later informed me that it requires the config option: > > CONFIG_RESET_ATTACK_MITIGATION > > It appears that setting this will allow the memory to be cleared on boot > up, which will definitely clear out the trace of the previous boot. > > Add this information under the trace_instance in kernel-parameters.txt > to let people know that this can cause issues. > > Link: > https://lore.kernel.org/all/[email protected]/ > > Reported-by: Hans de Goede <[email protected]> > Signed-off-by: Steven Rostedt (Google) <[email protected]>
Thanks, patch looks good to me: Reviewed-by: Hans de Goede <[email protected]> Regards, Hans > --- > Documentation/admin-guide/kernel-parameters.txt | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt > b/Documentation/admin-guide/kernel-parameters.txt > index bb48ae24ae69..f9b79294f84a 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -6850,6 +6850,9 @@ > > reserve_mem=12M:4096:trace > trace_instance=boot_map^traceoff^traceprintk@trace,sched,irq > > + Note, CONFIG_RESET_ATTACK_MITIGATION can force a memory > reset on boot which > + will clear any trace that was stored. > + > See also Documentation/trace/debugging.rst > >
