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[Bug #763] serial input escape sequence recognition issues

From: nobody
Subject: [Bug #763] serial input escape sequence recognition issues
Date: Wed, 03 Jul 2002 15:25:15 -0400

=================== BUG #763: LATEST MODIFICATIONS ==================

Changes by: Yoshinori K. Okuji <address@hidden>
Date: 2002-Jul-03 19:25 (GMT)

            What     | Removed                   | Added
          Resolution | None                      | Fixed
              Status | Open                      | Closed

=================== BUG #763: FULL BUG SNAPSHOT ===================

Submitted by: ilgiz                     Project: grub                           
Submitted on: 2002-Jun-27 05:14
Category:  Terminal                     Severity:  Ordinary                     
Priority:  Normal                       Bug Group:  Action Request              
Resolution:  Fixed                      Assigned to:  okuji                     
Status:  Closed                         Release:  2002-06-26                    
Reproducibility:  Intermittent          Planned Release:  0.93                  

Summary:  serial input escape sequence recognition issues

Original Submission:  a) The serial input escape sequence recognition delay 
on CPU speed.

b) The sequence translation is not invoked on each character read.
This means the eascape recognition delay will slow down alphanumeric

A patch that restores the original behavior of the serial input 
mechanism is attached.

Follow-up Comments

Date: 2002-Jul-03 18:49             By: ilgiz

Fine to me!

Date: 2002-Jul-03 18:46             By: okuji
Thanks for your explanation. I mistook currticks for

As for delays for non-"escape sequences", they should be
negligible, as they are at most some ten milliseconds.
In reality, you shouldn't even notice the extra delays.

BTW, would you mind closing this report? If all the problem
has gone, I'd like to close it.


Date: 2002-Jul-03 18:09             By: ilgiz
Everything is OK now on a Geode board at 115200 bps and 9600 bps.

To clear the suspicions against the original timer based implementation, the 
currticks() readings have resolution of 1/18 sec, so the escape sequence wait 
period was 1/9 sec.

The patch didn't refresh the wait timer once a part of valid escape sequence 
was received.  On the positive side, it didn't wait at all when any other 
sequence such as single alphanumeric character was received.

Date: 2002-Jul-02 23:44             By: okuji
I've modified the logic a bit. Could you try?

BTW, the reason why I don't want to incorporate your patch
is not because of the size. Rather, I didn't like the
previous implementation, because it waited for at most
two seconds. That was really irritating. So I'm attempting
to add a delay, as short as possible.


Date: 2002-Jul-02 16:38             By: ilgiz

All my difficulties were due to my own attempt to restore the wait escape 
sequence policy which existed before terminal code streamlining.

However, when I reverted my patch I found that after holding an arrow key in 
the command line for few seconds I was brought into the boot entry selection 
menu.  I think that could be due to the wait loop being too fast.  Will the 
115200 bps rate produce intervals of hundreds microseconds?  And what if I use 
a slower bit rate?

On reapplying my patch the problem has gone.  The patch may not be efficient in 
terms of amount of code.  It adds 96 bytes to stage2.

Date: 2002-Jun-29 20:57             By: okuji
Could you tell me what difficulty you have?
I thought the delay would be at most some microseconds,
even on an old 386 box.


File Attachments

Date: 2002-Jun-27 05:14  Name: grub-serial-escape.diff  Size: 3KB   By: ilgiz
a patch for better (former) serial input escape sequence recognition

For detailed info, follow this link:

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