[U-Boot] Question about Netconsole

[Jared Lewis]

Hi Detlev-

I just wanted to let you know that I got Netconsole to work on my board.
It turned out that the NetLoop routine was halting and initialing the
TSEC driver over and over as part of the packet reception process.  This
was causing the interface to go up and down over and over and the
packets were getting missed.  My temporary workaround has been to update
the tsec init and halt routines so that they don't do anything if stdin
is configured to "nc" (I figure that the interface is already in use so
it doesn't need to be updated).  This seems to solve my problem for the
time being and lets me continue on.  

Thank you for your suggestion.  I really appreciate your help.

Jared

-----Original Message-----
From: Detlev Zundel [mailto:dzu at denx.de] 
Sent: Friday, August 21, 2009 5:58 AM
To: Jared Lewis
Cc: u-boot at lists.denx.de
Subject: Re: [U-Boot] Question about Netconsole

Hi Jared,

> I have been having troubles getting Netconsole to work on eTSEC2 of a
> MPC8548 chip.  I was hoping that maybe someone here might be able to
> help me. 
>
> I'm currently using U-Boot v2009.01.  Using the bash script code
located
> in the README.Netconsole file, I have been able to successfully
transmit
> data from the 8548 to my host machine over netcat (using v0.7.1 on
> Fedora Core 11).  I've tested that this path works consistently by
only
> piping stdout to 'nc'.  
>
> My problem comes when I try to send data from the host machine to the
> 8548 (piping stdin to 'nc').  It seems like the data is getting
> transmitted by Netconsole (verified using wireshark), but it isn't
> getting consistently received by U-Boot.  I set the ET_DEBUG flag to 1
> so that I could get extra debug information.  On rare occasions I have
> seen that packets are getting received, but this is very rarely.  I do
> know that the connection is OK.  I am able to transfer files using
tftp
> without any problems.  On one occasion I was able to print out an
> environment variable (a small victory), but it happened randomly.  
>
> Does anyone have any idea why this might be happening?  Any help would
> be greatly appreciated.

You should check what your actual network driver is doing.  As U-Boot is
not interrupt driven, the big question is if and how packets on the
network
interface are buffered when U-Boot is not currently idle waiting.

Unfortunately I have to admit that I do not know the exact control flow
of netconsole coupled to the tsec driver, but what you could do is to
trace tsec_halt and startup_tsec.  Maybe they are called too often
and/or
take too long...

Cheers
  Detlev

-- 
Some people unfortunately like  jumping up and down about spaces but not
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than bad
poetry written in beautiful handwriting, and I think the same is true of
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           -- Alan Cox <20090701130018.115ce0ea at lxorguk.ukuu.org.uk>
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