lkml.org 
[lkml]   [2022]   [Apr]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH v6 06/17] timekeeping: add raw clock fallback for random_get_entropy()
Date
On Sat, Apr 23 2022 at 23:26, Jason A. Donenfeld wrote:
> The addition of random_get_entropy_fallback() provides access to
> whichever time source has the highest frequency, which is useful for
> gathering entropy on platforms without available cycle counters. It's
> not necessarily as good as being able to quickly access a cycle counter
> that the CPU has, but it's still something, even when it falls back to
> being jiffies-based.
>
> In the event that a given arch does not define get_cycles(), falling
> back to the get_cycles() default implementation that returns 0 is really
> not the best we can do. Instead, at least calling
> random_get_entropy_fallback() would be preferable, because that always
> needs to return _something_, even falling back to jiffies eventually.
> It's not as though random_get_entropy_fallback() is super high precision
> or guaranteed to be entropic, but basically anything that's not zero all
> the time is better than returning zero all the time.
>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Theodore Ts'o <tytso@mit.edu>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Not that I care much, but in general taking over authorship w/o
attribution via Suggested-by or such is frowned upon.

Thanks,

tglx

\
 
 \ /
  Last update: 2022-04-25 14:38    [W:0.332 / U:0.192 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site