[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-Id: <20240709074434.d3ff058a396d7020fa04f7e9@kernel.org>
Date: Tue, 9 Jul 2024 07:44:34 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Beau Belgrave <beaub@...ux.microsoft.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, rostedt@...dmis.org,
mhiramat@...nel.org, corbet@....net, linux-trace-kernel@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH] Documentation: Document user_events ioctl code
On Wed, 3 Jul 2024 16:13:43 -0700
Beau Belgrave <beaub@...ux.microsoft.com> wrote:
> On Wed, Jul 03, 2024 at 06:58:03PM -0400, Mathieu Desnoyers wrote:
> > On 03-Jul-2024 10:25:01 PM, Beau Belgrave wrote:
> > > The user events trace subsystem uses the 0x2A/'*' code for ioctls. These
> > > are published via the uapi/linux/user_events.h header file.
> > >
> > > Add a line indicating user events as the owner of the 0x2A/'*' code and the
> > > current sequence numbers that are in use (00-02).
> > >
> > > Signed-off-by: Beau Belgrave <beaub@...ux.microsoft.com>
> > > ---
> > > Documentation/userspace-api/ioctl/ioctl-number.rst | 2 ++
> > > 1 file changed, 2 insertions(+)
> > >
> > > diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
> > > index a141e8e65c5d..191609fe4593 100644
> > > --- a/Documentation/userspace-api/ioctl/ioctl-number.rst
> > > +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
> > > @@ -97,6 +97,8 @@ Code Seq# Include File Comments
> > > '%' 00-0F include/uapi/linux/stm.h System Trace Module subsystem
> > > <mailto:alexander.shishkin@...ux.intel.com>
> > > '&' 00-07 drivers/firewire/nosy-user.h
> > > +'*' 00-02 uapi/linux/user_events.h User Events Subsystem
> >
> > You may want to consider reserving a wider sequence number range to plan
> > ahead for future extensions to user events. This way you won't end up
> > having to jump over sequence numbers eventually reserved by others
> > within the '*' code.
> >
> > Thanks,
> >
> > Mathieu
>
> Yeah, I thought about that, but really didn't know how greedy we could
> be. At first I had all, but then thought we would never use all of that
> sequence. We'll likely want a few more for libside integration.
>
> Maybe I'll grab the first 16, that should leave a lot for others and
> give us quite bit of growing room.
I think that sounds reasonable, there is a sentence in the same file:
----
If you are writing a driver for a new device and need a letter, pick an
unused block with enough room for expansion: 32 to 256 ioctl commands.
----
Maybe you can reserve a block for 32 ioctl.
Thank you,
>
> How many do you think we'll need for libside? I think we'd only need 2-3
> personally.
>
> Thanks,
> -Beau
>
> >
> >
> > > + <mailto:linux-trace-kernel@...r.kernel.org>
> > > '1' 00-1F linux/timepps.h PPS kit from Ulrich Windl
> > > <ftp://ftp.de.kernel.org/pub/linux/daemons/ntp/PPS/>
> > > '2' 01-04 linux/i2o.h
> > > --
> > > 2.34.1
> > >
> >
> > --
> > Mathieu Desnoyers
> > EfficiOS Inc.
> > http://www.efficios.com
--
Masami Hiramatsu (Google) <mhiramat@...nel.org>
Powered by blists - more mailing lists