lkml.org 
[lkml]   [2024]   [Apr]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: API break, sysfs "capability" file
On Tue, Apr 09, 2024 at 10:19:09AM +0200, Lennart Poettering wrote:
> All I am looking for is a very simple test that returns me a boolean:
> is there kernel-level partition scanning enabled on this device or
> not.

And we can add a trivial sysfs attribute for that.

> At this point it's not clear to me if I can write this at all in
> a way that works reasonably correctly on any kernel since let's say
> 4.15 (which is systemd's "recommended baseline" right now).
>
> I am really not sure how to salvage this mess at all. AFAICS there's
> currently no way to write such a test correctly.

You can't. Maybe that's a lesson to not depend on undocumented internal
flags exposed by accident by a weirdo interface. Just talk to people.

> I think it would be nice if the "capabilities" thing would be brought
> back in a limited form. For example, if it would be changed to start
> to return 0x200|0x1000 for part scanning is off, 0x1000 when it is on.
>
> That would then mean we return to compatibility with Linux <= 5.15,
> but the new 0x1000 bit would tell us that the information is
> reliable. i.e. if userspace sees 0x1000 being set we know that the
> 0x200 bit is definitely correct. That would then just mean that
> kernels >= 5.16 until today are left in the cold...

At this point we're just better off with a clean new interface.
And you can use the old hack for < 5.15 if you care strongly enough
or just talk distros into backporting it to make their lives easier.

\
 
 \ /
  Last update: 2024-04-09 16:16    [W:0.104 / U:2.656 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site