On Wed, Sep 4, 2013 at 8:40 PM, Jonathan Austin <[email protected]> wrote:
> 'top' works on ARM with virtio console. I've just done some new testing
> and with the serial console emulation and I see the same as you're reporting.
> Previously with the 8250 emulation I'd booted to a prompt but didn't actually
> test top...
>
> I'm looking in to fixing this now... Looks like I need to find the right place
> from which to call serial8250_flush_tx now that it isn't getting called every
> tick.
>
> I've done the following and it works fixes 'top' with serial8250:
> -------8<----------
> diff --git a/tools/kvm/hw/serial.c b/tools/kvm/hw/serial.c
> index 931067f..a71e68d 100644
> --- a/tools/kvm/hw/serial.c
> +++ b/tools/kvm/hw/serial.c
> @@ -260,6 +260,7 @@ static bool serial8250_out(struct ioport *ioport, struct
> kvm *kvm, u16 port,
> dev->lsr &= ~UART_LSR_TEMT;
> if (dev->txcnt == FIFO_LEN / 2)
> dev->lsr &= ~UART_LSR_THRE;
> + serial8250_flush_tx(kvm, dev);
> } else {
> /* Should never happpen */
> dev->lsr &= ~(UART_LSR_TEMT | UART_LSR_THRE);
>
> ------------->8-----------
>
> I guess it's a shame that we'll be printing each character (admittedly the
> rate will always be
> relatively low...) rather than flushing the buffer in a batch. Without a
> timer, though, I'm
> not sure I see a better option - every N chars doesn't seem like a good one
> to me.
>
> If you think that looks about right then I'll fold that in to the patch
> series, probably also
> removing the call to serial8250_flush_tx() in serial8250__receive.
Yeah, looks good to me and makes top work again.
Pekka
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