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RE: Anyone actively working on gzip compression in LKCD?

To: "Matt D. Robinson" <yakker@xxxxxxxxxxx>
Subject: RE: Anyone actively working on gzip compression in LKCD?
From: "Tony Dziedzic" <Tony.Dziedzic@xxxxxxxxxxxx>
Date: Fri, 19 Oct 2001 14:33:56 -0400
Cc: <lkcd@xxxxxxxxxxx>
Sender: owner-lkcd@xxxxxxxxxxx
Thread-index: AcFYv+M9XBUUriwMSgqsJU7UCBvvngACrvgA
Thread-topic: Anyone actively working on gzip compression in LKCD?
Hi Matt:

That would be fine with me.  I'll e-mail you in a separate reply a
tarball containing my current drivers/dump directory that writes
gzip-compressed dumps (based on LKCD 4 release).  I'll also include a
quick and dirty version of kl_cmp.c that can read gzip-compressed data.
Until the zlib in kernel issue is resolved I simply grabbed a copy of
the zlib code from drivers/net and dumped it in drivers/dump as
zlib_dump.c.

One caveat that Dave Anderson at MCLinux pointed out: dump_gzip will
need to avoid calling the gz compression code when the page being
written is the current stack page.  Since the compression code uses (and
modifies) stack variables, the data that is being compressed will be
modified, resulting in a subsequent Z_DATA_ERROR when uncompressing that
page.  The nasty side-effect of this issue is that a backtrace of the
current task fails.  Other than that, my modified lcrash seemed happy
with a gzip-compressed dump.

I'll fix this issue within the next few days and get an updated
dump_gzip.c out to you.

Tony

> -----Original Message-----
> From: Matt D. Robinson [mailto:yakker@xxxxxxxxxxx]
> Sent: Friday, October 19, 2001 1:07 PM
> To: Tony Dziedzic
> Cc: lkcd@xxxxxxxxxxx
> Subject: Re: Anyone actively working on gzip compression in LKCD?
> 
> 
> 
> I currently am, but I'm waiting for some of this stuff with
> zlib in the kernel to finalize.    Looks like you've taken
> my initial check-ins and moved on them.  Cool.
> 
> Heh. :)  How about this, do you want to do the kernel space, and
> I'll add the 'lcrash' support?  I need to restructure 'lcrash' to
> handle multiple dump types anyway ...
> 
> |>Thanks,
> |>Tony Dziedzic
> |>Storigen Systems, Inc.
> 
> Thanks, Tony.
> 
> --Matt
> 
> 

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