[Skiboot] [PATCH] fast-reboot: improve integrity of fast reboots

[Stewart Smith]

Nicholas Piggin <npiggin at gmail.com> writes:
> On Fri, 23 Feb 2018 11:04:51 +1100
> Stewart Smith <stewart at linux.vnet.ibm.com> wrote:
>
>> Nicholas Piggin <npiggin at gmail.com> writes:
>> > This is a start on some basic checks that might detect firmware
>> > problems that call for a full IPL. The patch is pretty rough at
>> > the moment but it's just for comments.
>> >
>> > - Checksum text and most read-only data, and verify that against
>> >   checksum taken at IPL.
>> >
>> > - Check integrity of memory allocation structures and freelists.  
>> 
>> Good idea.
>> 
>> > - Zeroes most OS memory (should be parallelised).  
>> 
>> Been meaning to do this for a while. I wonder how much time it really
>> takes on big systems... Could be worth doing in parallel I guess.
>
> Just tested in userpsace a single CPU can memset about 32GB/s, and
> multiple on the same node can get 4x that. Multiple nodes should
> scale pretty linearly.
>
> A fully populated AC922 would be 64 seconds vs 8 seconds, so it will
> get noticable.

Yeah, that's worth it.

-- 
Stewart Smith
OPAL Architect, IBM.