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Re: [PATCH] hw/char/pl011: Output characters using best-effort mode

From: Peter Maydell
Subject: Re: [PATCH] hw/char/pl011: Output characters using best-effort mode
Date: Fri, 21 Feb 2020 12:44:29 +0000

On Fri, 21 Feb 2020 at 11:44, Paolo Bonzini <address@hidden> 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?

-- PMM

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