First kernel version with uring sockets support

First kernel version with uring sockets support

[Dmitry Sychov]

It's unclear starting from what version the kernel and headers
were updated with sockets support(IORING_OP_ACCEPT etc).

I just checked today 2020/01/22 Focal Rossa Ubuntu and the last OP is
only IORING_OP_TIMEOUT (still on kernel 5.4.0-12) ;(

So maybe it's a good idea to comment-update every io_uring.h OP with
minimum kernel version requirement...

p.s. Not every Linux user is a kernel hacker ;)

Re: First kernel version with uring sockets support

[Jens Axboe]

On 1/22/20 11:08 AM, Dmitry Sychov wrote:
> It's unclear starting from what version the kernel and headers
> were updated with sockets support(IORING_OP_ACCEPT etc).
> 
> I just checked today 2020/01/22 Focal Rossa Ubuntu and the last OP is
> only IORING_OP_TIMEOUT (still on kernel 5.4.0-12) ;(

Yeah, you'll need 5.5 for that.

> So maybe it's a good idea to comment-update every io_uring.h OP with
> minimum kernel version requirement...

You mean the one in liburing?

> p.s. Not every Linux user is a kernel hacker ;)

Definitely! This will be solved with 5.6 that introduces a probe
command, so you can query the running kernel for what opcodes it
supports. For now, it's not that easy, unfortunately...

-- 
Jens Axboe

Re: First kernel version with uring sockets support

[Dmitry Sychov]

> You mean the one in liburing?

I'am referring to
https://github.com/frevib/io_uring-echo-server/blob/master/src/include/liburing/io_uring.h
with sockets OPs as the latest interface reference, thinking it will
help the io_uring newcomers if
IORING_OP_* lines will have corresponding comments of the minimum
kernel requirement for now and the future.

For example I was almost totally sure that sockets were the first
uring-supported thing.

> Yeah, you'll need 5.5 for that.

I see, thanks :)

On Wed, Jan 22, 2020 at 9:11 PM Jens Axboe <axboe@kernel.dk> wrote:
>
> On 1/22/20 11:08 AM, Dmitry Sychov wrote:
> > It's unclear starting from what version the kernel and headers
> > were updated with sockets support(IORING_OP_ACCEPT etc).
> >
> > I just checked today 2020/01/22 Focal Rossa Ubuntu and the last OP is
> > only IORING_OP_TIMEOUT (still on kernel 5.4.0-12) ;(
>
> Yeah, you'll need 5.5 for that.
>
> > So maybe it's a good idea to comment-update every io_uring.h OP with
> > minimum kernel version requirement...
>
> You mean the one in liburing?
>
> > p.s. Not every Linux user is a kernel hacker ;)
>
> Definitely! This will be solved with 5.6 that introduces a probe
> command, so you can query the running kernel for what opcodes it
> supports. For now, it's not that easy, unfortunately...
>
> --
> Jens Axboe
>

Re: First kernel version with uring sockets support

[Jens Axboe]

On 1/22/20 11:22 AM, Dmitry Sychov wrote:
>> You mean the one in liburing?
> 
> I'am referring to
> https://github.com/frevib/io_uring-echo-server/blob/master/src/include/liburing/io_uring.h
> with sockets OPs as the latest interface reference, thinking it will
> help the io_uring newcomers if
> IORING_OP_* lines will have corresponding comments of the minimum
> kernel requirement for now and the future.

The above obviously isn't mine, but it's probably forked/pulled from my
liburing.

I think the best thing to do here is update the io_uring_enter(2)
man page, since it has opcode descriptions. In those descriptions,
each of them should include "Supported since version 5.x" to make
this perfectly clear.

Longer term, I expect the probe to be the most useful for applications.

I don't want to change io_uring.h itself, as I've keep that sane so it
can simply be copied from the kernel repository to liburing. I intend
to keep it that way.

-- 
Jens Axboe