Re: TTY Flip buffers

Linux Lists (lists@cyclades.com)
Wed, 24 Nov 1999 12:12:48 -0800 (PST)

On Wed, 24 Nov 1999, Theodore Y. Ts'o wrote:
>
> Note also that the flip buffer is only there to improve interrupt
> latency and efficiency in handling small numbers of characters. For
> some cards, you may be better off bypassing it altogether. For example,
> the Rocketport driver has huge on-board FIFO's, is polled on the
> clock tick, and the driver can read in a hundred character or more at a
> time. Therefore, there's no point using the flip buffer, and so the
> Rocketport driver simply calls the line discpline receive_buf() directly.

Hmmmm ... I like this idea very much ... :))

Just one question: I looked at n_tty_receive_buf and I didn't see any
protection / warn back mechanism (the function is void) as to "what if the
room in the TTY buffer is too small to store all the data passed
directly by the driver". What happens if the driver passes a data amount
that's bigger than the available room in the TTY buffer??

I also looked at the Rocketport driver, and I didn't see anywhere a check
for this available TTY buffer space. Is there a way to do that?? Should we
do that??

Regards,
Ivan

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