[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: term bugs
Re: term bugs
Mon, 2 Sep 2002 15:48:04 -0400 (EDT)
> I don't know if this is a problem or not. isatty should return if the file
> descriptor is associated with a terminal device, but is the master a
> terminal device in that sense? Linux returns YES.
No, it's not. BSD also returns no.
> This is exactly the same problem as when doing a cut & paste of more than
> 300 bytes in screen. We really should fix that, as all other sane systems
> allow at least 512 bytes. This is obviously related to the 300 byte hi
> watermark in term, but I am not sure if the 300 byte queue should work
That is the MAX_INPUT limit, which is also small (255) in Linux, though I
am not sure whether it is actually enforced. That's the limit on the raw
input queue for a real terminal device. I guess something different is
being done for ptys.
> When the writer goes to sleep, it first wakes up the reader with
> bottom->start_output, should that do the job already? I am a bit unsure how
> the code is supposed to work.
I too am just reading the code now to know what to tell you. It wakes
anyone blocked in io_read or io_select, but that doesn't guarantee that
they will get scheduled, get the lock, and consume the queue before the
writer wants to write more.
> The limit in Linux seems to be 8061, after that it blocks.
>From what I can see in kernel source, pty master writes are copied into a
temporary buffer of up to 2k and then inserted in the tty's buffer of 4k.
But there is a lot of hair in how all the various buffers are used and some
weird kludges in the pty stuff.
- term bugs, Marcus Brinkmann, 2002/09/02
- Re: term bugs,
Roland McGrath <=