Remove flight recorder

David Boutcher boutcher at
Tue Dec 2 00:09:46 EST 2003

owner-linuxppc64-dev at wrote on 11/30/2003 08:42:11 PM:
> Hi all,
> During the porting of the 2.6 kernel to iSeries (or the iSeries kernel
> to 2.6 :-)) I have been #defining out the flight recorder stuff as I
> had no idea what it was for.  Anton suggested that it may have been a
> useful bringup tool, but that we don't have the necessary tools to use
> it.
> Does anyone mind if I just excise the flight recorder code (from iSeries
> in particular)?

Hi Stephen,

Which flight recorder stuff?  Do you mean the HvCall_WriteLogBuffer stuff?
In that case, it probably should be left in.  Those calls write the console
output to a hypervisor buffer that can be retreived later through a couple
of different mechanisms.  One of the key uses for that is if you don't have
a console connected when your linux crashes, you can come in later and dump
the last console output.  It is also handy when linux crashes, because
frequently not all output makes it out through the tortuous console
connection, and you can dump the tail end of any kernel output.

To dump the hypervisor log buffer, type ctrl-x ctrl-x on the console
screen, or there is a path through the green-screen SST screens if you
really want to use it.

If I just answered the wrong question, remind me which flight recorder you
are pulling out?


Dave Boutcher
IBM Linux Technology Center

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