Re: [Xen-devel] [PATCH] Fix xenconsole's "Could not read tty from store"

[John Levon <levon@xxxxxxxxxxxxxxxxx>]

On Tue, Dec 18, 2007 at 06:07:17PM +0000, Samuel Thibault wrote:

> > > + if (tcgetattr(master, &term) < 0) {
> > > +         err = errno;
> > 
> > Please use the slave not the master. It doesn't matter on Linux but it's
> > critical on Solaris.
> 
> What is the Solaris reason for this?  It really looks we can't afford
> closing the slave end on Linux (hence leak it) or not open it at all
> (and then we can't tcgetattr on it).

On Linux, both ends of a pty act like a pseudo-terminal and you can do
term-like things on both ends (and there's apparently small variations
in the effect they have). This is not true on STREAMS-based systems. In
particular, you have to push the "ptem" module before you can use any of
the tcget/setattr() functions (look at openpty()).

I'm working on a new version of the patch that just keeps the slave open
(without leaking it) on both platforms - I think this should cover these
differences sufficiently.

regards
john

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