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From:   Alexander Aring <aahringo@redhat.com>
Date:   Tue, 8 Jun 2021 17:03:16 -0400
Message-ID: <CAK-6q+g3_9g++wQGbhzBhk2cp=0fb3aVL9GoAoYNPq6M4QnCdQ@mail.gmail.com>
Subject: Re: quic in-kernel implementation?
To:     Stefan Metzmacher <metze@samba.org>
Cc:     Steve French <smfrench@gmail.com>,
        =?UTF-8?Q?Aur=C3=A9lien_Aptel?= <aaptel@suse.com>,
        Network Development <netdev@vger.kernel.org>,
        linux-nfs <linux-nfs@vger.kernel.org>,
        CIFS <linux-cifs@vger.kernel.org>,
        Leif Sahlberg <lsahlber@redhat.com>,
        Steven Whitehouse <swhiteho@redhat.com>
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Hi,

On Tue, Jun 8, 2021 at 3:36 AM Stefan Metzmacher <metze@samba.org> wrote:
...
>
> > 2) then switch focus to porting a smaller C userspace implementation of
> > QUIC to Linux (probably not msquic since it is larger and doesn't
> > follow kernel style)
> > to kernel in fs/cifs  (since currently SMB3.1.1 is the only protocol
> > that uses QUIC,
> > and the Windows server target is quite stable and can be used to test against)> 3) use the userspace upcall example from step 1 for
> > comparison/testing/debugging etc.
> > since we know the userspace version is stable
>
> With having the fuse-like socket before it should be trivial to switch
> between the implementations.

So a good starting point would be to have such a "fuse-like socket"
component? What about having a simple example for that at first
without having quic involved. The kernel calls some POSIX-like socket
interface which triggers a communication to a user space application.
This user space application will then map everything to a user space
generated socket. This would be a map from socket struct
"proto/proto_ops" to user space and vice versa. The kernel application
probably can use the kernel_FOO() (e.g. kernel_recvmsg()) socket api
directly then. Exactly like "fuse" as you mentioned just for sockets.

I think two veth interfaces can help to test something like that,
either with a "fuse-like socket" on the other end or an user space
application. Just doing a ping-pong example.

Afterwards we can look at how to replace the user generated socket
application with any $LIBQUIC e.g. msquic implementation as second
step.

- Alex