From owner-freebsd-hackers  Tue Aug 28 10:23:52 2001
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From: "Steven Ames" <steve@virtual-voodoo.com>
To: "Andrew Gallatin" <gallatin@cs.duke.edu>
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	"Jim Bryant" <kc5vdj@yahoo.com>, <FreeBSD-hackers@FreeBSD.ORG>
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Subject: Re: TCSH bug...
Date: Tue, 28 Aug 2001 12:19:56 -0500
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From: "Andrew Gallatin" <gallatin@cs.duke.edu>
> Actually, it is a tcsh bug. Try playing with the MALLOC_OPTIONS
> env. variable in -stable.  Specifically, set it to 'AJ' & I bet it will
> drop core in -stable.  Eg:
> [EXAMPLE DELETED]
> Note that -current has malloc options 'AJ' on by default to catch just
> this kind of bug.


Ah. That wasn't clear from 'man malloc' under CURRENT. Setting
MALLOC_OPTIONS = "J" (on -STABLE) causes the dump. Now
according to the man page for malloc:

     J       Each byte of new memory allocated by malloc(), realloc() or
             reallocf() as well as all memory returned by free(), realloc()
or
             reallocf() will be initialized to 0xd0.  This options also sets
             the ``R'' option.  This is intended for debugging and will
impact
             performance negatively.

This option is used to catch places where the code makes assumptions
about the contents of malloc memory? (e.g. that it is zeroed)?

I will submit a problem report to Christos but I want to make sure
that I can explain exactly what is happening and why...

-Steve


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