Re: ns8250: UART FCR is broken

From: void <void_at_f-m.fm>
Date: Thu, 27 Oct 2022 14:42:52 UTC 
On Wed, Oct 26, 2022 at 02:15:29PM -0700, Colin Percival wrote:

>Indeed, looking at usr.sbin/bhyve/uart_emul.c it looks like FCR_XMT_RST is
>not emulated.  This is different from Firecracker, which doesn't emulate
>either anything from the FCR and where I was seeing the receive side not
>being flushed, but I'm glad my warning was able to flag a bug. :-)
>
>If "void" is comfortable with kernel hacking, it would be great to confirm
>that the warning is indeed coming from the transmit side not being flushed;
>a printf("drain = %d\n", drain); would be sufficient.
>
>And yes, only emitting this warning once per device (or once per boot?)
>would probably be good.

I'm happy to do some kernel hacking with this vm. Tell me what I need to
do.

Thanks,
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