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Re: [gpsd-dev] What is our current bug state?
From: |
Eric S. Raymond |
Subject: |
Re: [gpsd-dev] What is our current bug state? |
Date: |
Sun, 1 Feb 2015 23:33:08 -0500 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
Hal Murray <address@hidden>:
>
> address@hidden said:
> > My current belief is that solving that problem will require gpsd to go to
> > using blocking I/O rather than nonblocking, because setting VTIME is only
> > effective when blocking I/O is enabled. The trouble is that I don't know
> > how to make that change in a way that won't cause device opens to hang hard.
>
> The context is opening things like /dev/tty. Right?
>
> I had similar problems ages ago. I don't remember the exact context.
>
> My solution was to use O_NONBLOCK to open the tty, then turn on CLOCAL, then
> close and reopen without O_NONBLOCK.
>
> That may be a wild goose chase, YMMV, etc. That was on Linux. I don't know
> how portable it is.
Interesting. I tried just removing O_NOBLOCK from gpsd's tty opens, and
it turns out that both gpsd and gpsmon work fine without that flag.
I thought they were more broken than they are because the first thing I tried
was the regression tests - and something inside gpsfake hangs. My next step
will be to groval through an strace dump trying to figure out why.
--
<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
Re: [gpsd-dev] What is our current bug state?, Hal Murray, 2015/02/01
Re: [gpsd-dev] What is our current bug state?, Greg Troxel, 2015/02/02