Re: [PATCH] ubi-utils: Implement a ubihealthd

[Richard Weinberger <richard@xxxxxx>]

Alex,

----- Ursprüngliche Mail -----
> Von: "Alexander Dahl" <ada@xxxxxxxxxxx>
> What is it exactly, which requires such a new Linux Kernel? The latest LTS is
> still v4.19 … ;-)

The new UBI machinery which allows userspace to control scrubbing was added in 5.2.

[..]

>> +	srand(seed);
>> +}
> 
> Is it really necessary to seed with getrandom() for just randomizing a list of
> PEBs? I know this is embedded, and seeding with the same time on each boot
> (those devices always start 1970 ;-) ) might be a bad idea for crypto, but for
> just shuffling a PEB list to spread those tests randomly?

Yes. The list really needs to be shuffled.

Before getrandom() we used time() and faced exactly the case where customer boards
always started with the same permutation because they had no RTC.

If you don't shuffle the list you cannot have the daemon stateless.

For example, if the board reboots once a day and completing the PEB list
needs a week you will always check the same PEBs and miss the same ones.
 
> I'd really like to test this daemon, but also for older systems not running
> bleeding edge BSPs. Would you accept patches to make it work with let's say
> kernel v4.9 and glibc v2.20 … O:-)

Well, you need to backport the UBI changes anyway.
But patches to make it work on other/older libcs are happily accepted
if they are sane. :-)

Thanks,
//richard

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