VirtualSerial no read requests?

NTDEV
1

I have a virtual serial based the Microsoft sample (
https://github.com/Microsoft/Windows-driver-samples/tree/master/serial/VirtualSerial)
modified to strip out the ringbuffer and replace it with a duplex named
pipe.

At the moment on the other end of the pipe I just have a test app that
echos everything back that is read from the pipe.

The problem I have is that some terminals start sending read requests (and
can see the echo) but some do not.

Maybe there is some IOCTL that is not completed in the way a terminal
expects it to be or something?

Has anyone else encountered this?

2

I though there were serial device IOCTLs that queried the buffer state, so the app may not issue a read until it finds there is actually something to read. A polling based architecture like this makes the terminal application simpler, especially if it’s platform portable code.

Jan

From: on behalf of Daniel Newton
Reply-To: Windows List
Date: Friday, October 28, 2016 at 4:14 PM
To: Windows List
Subject: [ntdev] VirtualSerial no read requests?

I have a virtual serial based the Microsoft sample (https://github.com/Microsoft/Windows-driver-samples/tree/master/serial/VirtualSerial) modified to strip out the ringbuffer and replace it with a duplex named pipe.

At the moment on the other end of the pipe I just have a test app that echos everything back that is read from the pipe.
The problem I have is that some terminals start sending read requests (and can see the echo) but some do not.
Maybe there is some IOCTL that is not completed in the way a terminal expects it to be or something?
Has anyone else encountered this?
— NTDEV is sponsored by OSR Visit the list online at: MONTHLY seminars on crash dump analysis, WDF, Windows internals and software drivers! Details at To unsubscribe, visit the List Server section of OSR Online at