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Date:   Wed, 9 Jun 2021 09:48:18 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Stephen Hemminger <stephen@networkplumber.org>
Cc:     Alexander Aring <aahringo@redhat.com>,
        Stefan Metzmacher <metze@samba.org>,
        Steve French <smfrench@gmail.com>,
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        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>
Subject: Re: quic in-kernel implementation?
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On Tue, 8 Jun 2021 15:33:49 -0700 Stephen Hemminger wrote:
> On Tue, 8 Jun 2021 17:03:16 -0400
> > > 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.
> 
> Socket state management is complex and timers etc in userspace are hard.

+1 seeing the struggles fuse causes in storage land "fuse for sockets"
is not an exciting temporary solution IMHO..