From: Peter Maydell <peter.maydell@linaro.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Gavin Shan" <gshan@redhat.com>, "Marc Zyngier" <maz@kernel.org>,
"QEMU Developers" <qemu-devel@nongnu.org>,
qemu-arm <qemu-arm@nongnu.org>,
"Marc-André Lureau" <marcandre.lureau@gmail.com>,
"Shan Gavin" <shan.gavin@gmail.com>
Subject: Re: [PATCH] hw/char/pl011: Output characters using best-effort mode
Date: Fri, 21 Feb 2020 12:44:29 +0000 [thread overview]
Message-ID: <CAFEAcA-bHCLQGkFucY5RAY-mw9wFdDeOqCkcv0xgSRg-EYh9ew@mail.gmail.com> (raw)
In-Reply-To: <eedbac05-5a17-82e6-3cdc-c3b21983545b@redhat.com>
On Fri, 21 Feb 2020 at 11:44, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 21/02/20 11:21, Peter Maydell wrote:
> > Before you do that, I would suggest investigating:
> > * is this a problem we've already had on x86 and that there is a
> > standard solution for
> Disconnected sockets always lose data (see tcp_chr_write in
> chardev/char-socket.c).
>
> For connected sockets, 8250 does at most 4 retries (each retry is
> triggered by POLLOUT|POLLHUP). After these four retries the output
> chardev is considered broken, just like in Gavin's patch, and only a
> reset will restart the output.
>
> > * should this be applicable to more than just the socket chardev?
> > What's special about the socket chardev?
>
> For 8250 there's no difference between socket and everything else.
Interesting, I didn't know our 8250 emulation had this
retry-and-drop-data logic. Is it feasible to put it into
the chardev layer instead, so that every serial device
can get it without having to manually implement it?
thanks
-- PMM
next prev parent reply other threads:[~2020-02-21 12:45 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 6:01 [PATCH] hw/char/pl011: Output characters using best-effort mode Gavin Shan
2020-02-20 8:47 ` Philippe Mathieu-Daudé
2020-02-20 9:07 ` Gavin Shan
2020-02-20 9:10 ` Marc Zyngier
2020-02-20 10:10 ` Peter Maydell
2020-02-21 4:24 ` Gavin Shan
2020-02-21 9:09 ` Marc Zyngier
2020-02-23 23:57 ` Gavin Shan
2020-02-21 10:21 ` Peter Maydell
2020-02-21 11:44 ` Paolo Bonzini
2020-02-21 12:44 ` Peter Maydell [this message]
2020-02-21 13:09 ` Paolo Bonzini
2020-02-21 13:14 ` Peter Maydell
2020-02-21 18:15 ` Paolo Bonzini
2020-02-23 23:45 ` Gavin Shan
2020-02-23 23:26 ` Gavin Shan
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