Re: [PATCH 0/3] zram: Replace pr_* with dev_*

Joe Perches
2015-08-07T01:17:35Z

On Fri, 2015-08-07 at 09:05 +0900, Sergey Senozhatsky wrote:
> On (08/07/15 00:03), Salah Triki wrote:
> > This patchset replaces pr_* with dev_*. dev_* attach kernel messages to the right
> > device. In addition, patchs 1 and 2 add to messages the values of variables that trigger
> > errors.
[]
> I'd prefer to leave the messages the way they are. Changing anything
> visible to user space (api, eror codes, error messages, etc.) is a
> very risky business. You change the format of error messages and it
> smells like a big NO-NO.
>
> 'zram: Cannot initialise lzo compressing backend'
> --> 'block zram0: Cannot initialise lzo compressing backend'
>
>
> And there are even more dramatic changes:
> "Cannot change max compression streams\n"
> --> "Cannot change max compression streams to %d\n"
>
> "Can't change algorithm for initialized device\n"
> --> "Can't change algorithm to %s for initialized device\n"
>
>
> People already can have scripts doing `grep "zram:"` on dmesg or
> whatever. We cannot change this anymore.

That's not true at all.

Using grep on dmesg is specifically _not_ guaranteed
to remain stable between kernel versions.