From owner-freebsd-current  Thu Jul 22  7:24:26 1999
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Date: Fri, 23 Jul 1999 00:23:59 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199907221423.AAA25033@godzilla.zeta.org.au>
To: cracauer@cons.org, current@FreeBSD.ORG
Subject: Re: DDB: How to find address of static symbol?
Sender: owner-freebsd-current@FreeBSD.ORG
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X-Loop: FreeBSD.ORG

>I want to examine and switch a variable in ddb. The variable is static
>to a source file, I don't have a symbol in ddb.

You should have static symbols in ddb, except in the following broken
cases:

1) elf kernel booted with -d.  There are no symbols at the initial
   breakpoint because elf symbols are loaded by a sysinit.
2) elf kernel booted directly by boot2.  Static symbols require
   special handling which seems to only be done in boot/loader.
   I don't use boot/loader, so I had to fix this.  I use the pre-kld
   method of loading elf symbols (ddb/db_elf.c).  This also fixes
   (1).  It probably breaks symbols in modules.

>I see the address of the symbol with `nm /kernel | grep symname`, but
>the addresses listed here are obviously subject to file-specific
>offsets. The addresses show up twice and I can verify that the data is
>wrong when I just use the hex address in ddb.

The symbol values are offset in the file. but not in memory.

Bruce


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