Elsa MicroLink 33.6TQV on HP-UX 10.20 with vgetty

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Hi,

Lutz Jaenicke wrote:
> On Wed, Dec 03, 1997 at 08:49:24PM +0100, Gert Doering wrote:
> [...]
> > > after the select in io.c:wait_for_input(), that no data is ready for reading
> > > (read returns 0). This effect only happens, after the termio is reprogrammed
> > > in voice/libvoice/init.c:voice_init(). I have no experience with programming
> > > the serial line, but the problem seems to be related to the c_cc adjustments.
> > 
> > I dimly remember that we have seen this on some other platform as well.
> > It seems to be related to setting VTIME to something > 0.
> Yes, when I changed this in init.c to unbuffered(?) c_cc[VTIME]=0 select
> behaved as expected.

This is what I remembered, yes. Unfortunately, vgetty depends on VTIME>0
(at least that's what I remember -- don't forget that I didn't write a
single line of vgetty code, and have not much idea about its inner
workings...)

> > At that time, we did not fix it, because nobody had time (and partly
> > because I think that's a bug -- select() should return if there is 
> > *DATA*, not "if a subsequent read() won't block" - but then, select() 
> > isn't standardized *that* well...)
> Unfortunately the man page on HP-UX isn't that specific. It just says:
> ... 
> If the readfs argument is not a null pointer, it points to an object
> of type fd_set that on input specifies the file descriptors to be
> checked for being ready to read, and on output indicates which file
> descriptors are ready to read.
> ...

So, the question is, what does "ready to read" mean...

 a) "will not block"
 b) "there is data"

... I don't think it's "cast into stone" how select() should behave here.

[..]
> > > PS. Should I have spent more money? At home my Zyxel E2864ID works fine
> > > with Linux, even with the additional memory for fax receipts without PC :-)
> > I don't think a different modem would have made a difference. A different
> > operating system maybe :-)
> Even then I like my HP :-), but maybe I would be able to track it down more
> easily, if I would have the kernel source code, like at home :-)

Well... I don't like HP/UX... but SGI with Irix seems to be even more
vgetty-unfriendly ;-)

[I'm not sure why I dislike HP/UX so much. I think it has something to do
with very uncommon cursor key handling in "hpterm", with too many devices
for a single serial port, and weird cabling schemes on some platforms...]

gert

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Gert Doering - Munich, Germany      gert@greenie.muc.de
fax: +49-89-35655025    gert.doering@physik.tu-muenchen.de
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