Support for serial console on legacy free machines

Support for serial console on legacy free machines

[Khalid Aziz]

I am working on adding support for serial console on legacy free
machines. Legacy free machines are not expected to have the legacy COM
ports. The serial ports on these machines can exist in I/O space, memory
space or they could be PCI devices. This brings up the problem of
detecting where the serial console is. This problem is supposed to be
solved by ACPI 2.0 tables. The table that gives the details of serial
console is "Serial Port Console Redirection" (SPCR) table. This table
gives me almost all the information I need to initialize and use a
serial console. The bummer is this table was designed by Microsoft and
Microsoft owns the copyright on it. Microsoft primarily designed this
table for use by Whistler. Their copyright may cause potential problems
with using it in Linux. This makes me reluctant to use this table. I
would like to know how do others feel about using an ACPI table with
Microsoft copyright. I would like to try to push for another table in
ACPI spec that is free from copyright by any corporation and is simply a
part of spec, if most Linux developers are opposed to using a
copyrighted ACPI table.

Please ask questions if you need more info. URL for SPCR table
definition, if you would like to look at it, is
<http://www.microsoft.com/hwdev/headless/download/SerialPortRedir.zip>.

-- 
Khalid

====================================================================
Khalid Aziz                              Linux Systems Operation R&D
(970)898-9214                                        Hewlett-Packard
khalid@fc.hp.com                                    Fort Collins, CO

Re: Support for serial console on legacy free machines

[Simon Richter]

On Thu, 26 Jul 2001, Khalid Aziz wrote:

> The bummer is this table was designed by Microsoft and
> Microsoft owns the copyright on it.

This is an interface definition IMHO, so you cannot copyright it. But
IANAL.

   Simon

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Re: Support for serial console on legacy free machines

[Khalid Aziz]

Simon Richter wrote:
> 
> On Thu, 26 Jul 2001, Khalid Aziz wrote:
> 
> > The bummer is this table was designed by Microsoft and
> > Microsoft owns the copyright on it.
> 
> This is an interface definition IMHO, so you cannot copyright it. But
> IANAL.
> 
>    Simon
> 

That is a legal issue and I am not quite ready to go to battle with
Microsoft over a legal issue :-) From what I can see, the table
definition comes with a Microsoft copyright and terms of use license.

-- 
Khalid

====================================================================
Khalid Aziz                              Linux Systems Operation R&D
(970)898-9214                                        Hewlett-Packard
khalid@fc.hp.com                                    Fort Collins, CO

Re: Support for serial console on legacy free machines

[Rik van Riel]

On Thu, 26 Jul 2001, Khalid Aziz wrote:

> serial console. The bummer is this table was designed by Microsoft and
> Microsoft owns the copyright on it. Microsoft primarily designed this

Microsoft owns the copyright on that particular document.

If I were to give you an mp3 with descriptions of what
various bits to poke at you'd be free to do whatever you
want with that info ;)

In fact, I suspect you're already free to do whatever
you want with the info contained in the document...

Rik
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Re: Support for serial console on legacy free machines

[Khalid Aziz]

Rik van Riel wrote:
> 
> On Thu, 26 Jul 2001, Khalid Aziz wrote:
> 
> > serial console. The bummer is this table was designed by Microsoft and
> > Microsoft owns the copyright on it. Microsoft primarily designed this
> 
> Microsoft owns the copyright on that particular document.
> 
> If I were to give you an mp3 with descriptions of what
> various bits to poke at you'd be free to do whatever you
> want with that info ;)
> 
> In fact, I suspect you're already free to do whatever
> you want with the info contained in the document...
> 

You are possibly right. It would be better to use SPCR as opposed to
another equivalent table since every vendor is extremely likely to
include SPCR in their ACPI implementation in the firmware since
Microsoft would require it, which may not be the case with another
table. If everyone feels there is no problem with using SPCR as it is,
then I can release the code I have already done to support it. One thing
I should point out is since Microsoft owns the definition for SPCR (same
applies to DBGP which defines a Debug serial port), they can easily
change the defitnition of the table and Linux will have to play catch
up, although that situation would be nothing new. 

Here is an excerpt from the disclaimer in the table description document
for anyone interested:

"Disclaimer: The information contained in this document represents the
current view of Microsoft Corporation on the issues discussed as of  the
date of publication. Because Microsoft must respond to changing market
conditions, it should not be interpreted to be a commitment on  the part
of Microsoft, and Microsoft cannot guarantee the accuracy of any
information presented. This document is for informational purposes only.
MICROSOFT MAKES NO WARRANTIES, EXPRESS OR IMPLIED, IN THIS DOCUMENT.

Microsoft Corporation may have patents or pending patent applications,
trademarks, copyrights, or other intellectual property rights covering
subject matter in this document. The furnishing of this document does
not give you any license to the patents, trademarks,  copyrights, or
other intellectual property rights except as expressly provided in any
written license agreement from Microsoft Corporation.  

Microsoft does not make any representation or warranty regarding
specifications in this document or any product or item developed based
on these specifications. Microsoft disclaims all express and implied
warranties, including but not  limited to the implied warranties or
merchantability, fitness for a particular purpose and freedom from
infringement. Without limiting the generality of the foregoing,
Microsoft  does not make any warranty of any kind that any item
developed based on these  specifications, or any portion of a
specification, will not  infringe any copyright, patent, trade secret or
other intellectual property right of any person or entity in any
country. It is your responsibility  to seek licenses for such
intellectual property  rights where appropriate. Microsoft shall not be
liable for any damages arising out of or in  connection with the use of
these specifications, including liability for lost profit, business
interruption, or any other damages whatsoever."



-- 
====================================================================
Khalid Aziz                              Linux Systems Operation R&D
(970)898-9214                                        Hewlett-Packard
khalid@fc.hp.com                                    Fort Collins, CO

acpitbl bug

[Laurent Pinchart]

[-- Attachment #1: Type: text/plain, Size: 249 bytes --]

The acpitbl perl script doesn't display correctly the contents of the FADT 
table flags, due to a 3-byte reserved field which is not handled correctly in 
the show_table function.

I attached a patch to this e-mail.

Best regards,

Laurent Pinchart

[-- Attachment #2: patch --]
[-- Type: text/plain, Size: 754 bytes --]

diff -Naur old/acpitbl new/acpitbl
--- old/acpitbl	Tue Apr 25 16:37:11 2000
+++ new/acpitbl	Mon Jul 30 22:31:48 2001
@@ -64,13 +64,15 @@
 {
     local(*OUT, *desc, *data) = @_;
     my(%size_to_tmpl) =
-	("D1"=>"C", "D2"=>"S", "D4"=>"I",
-	 "X1"=>"C", "X2"=>"S", "X4"=>"I",
-	 "A4"=>"A4", "A6"=>"A6", "A8"=>"A8");
+	("D1"=>"C", "D2"=>"S",  "D4"=>"I",
+	 "X1"=>"C", "X2"=>"S",  "X3"=>"a3",
+	 "X4"=>"I", "A4"=>"A4", "A6"=>"A6",
+	 "A8"=>"A8");
     my(%size_to_fmt) =
 	("D1"=>"%d", "D2"=>"%d", "D4"=>"%d",
-	 "X1"=>"0x%02x", "X2"=>"0x%04x", "X4"=>"0x%08x",
-	 "A4"=>"%s", "A6"=>"%s", "A8"=>"%s");
+	 "X1"=>"0x%02x", "X2"=>"0x%04x", "X3"=>"0x%06x",
+	 "X4"=>"0x%08x", "A4"=>"%s", "A6"=>"%s",
+	 "A8"=>"%s");
 
     my($tmpl) = "";
     my($max_size) = 0;