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Date: Sun, 21 Oct 2001 00:39:13 -0400
From: Christopher Faylor <cgf AT redhat DOT com>
To: cygwin AT cygwin DOT com
Cc: bgat AT billgatliff DOT com
Subject: Re: [1.3.3] breaks serial i/o?
Message-ID: <20011021003913.A29884@redhat.com>
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On Sun, Oct 21, 2001 at 12:30:44AM -0400, Christopher Faylor wrote:
>On Sat, Oct 20, 2001 at 10:39:34PM -0400, Christopher Faylor wrote:
>>However, before we reach this drastic step, I'd *really* suggest at
>>least trying the 5.1 branch of gdb.  Your errors sound very similar
>>to others that were reported with ARM.  It is very possible that
>>they were fixed subsequent to 5.0.
>
>I have just spelunked through the cvs logs in the rdi-share directory
>and it looks like most relevant changes to gdb for arm/rdi did make
>it into gdb 5.0 so this probably is not going to hold out much promise.
>
>>From looking at gdb's code it seems like select is returning a TRUE
>for something to select on the serial line but when it is time to
>read something, apparently nothing is available.
>
>I guess I really will have to make a cable and connect my linux and
>windows systems to test this...

One suggestion for the gdb code -- add an '| O_BINARY' to all of the
opens of the serial line in unixcomm.c.  I can see a pathological
condition in cygwin where a VMIN setting will not be properly honored if
there is a readahead condition due to a '\n' -> '\r\n' conversion.

This could cause the code to block but even if it wasn't blocking, I
assume that you probably don't want to do newline conversions.

This probably isn't going to fix the problem since the default is for
cygwin to not do this kind of conversion on devices but it's best to be
safe anyway.

cgf

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