Date: Tue, 10 Mar 1998 15:04:08 -0800 From: John Polstra <jdp@polstra.com> To: ken@plutotech.com Cc: dyson@FreeBSD.ORG, current@FreeBSD.ORG Subject: Re: problems stripping kernels Message-ID: <199803102304.PAA21639@austin.polstra.com> In-Reply-To: <199803102018.NAA16119@panzer.plutotech.com> References: <199803102018.NAA16119@panzer.plutotech.com>
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In article <199803102018.NAA16119@panzer.plutotech.com>,
Kenneth D. Merry <ken@plutotech.com> wrote:
> I've noticed a problem stripping kernels since John's changes on
> Saturday went in. (and it wasn't fixed by version 1.46 of ufs_readwrite.c
> yesterday)
>
> Basically, I config my kernels with -g, and then use strip -d to
> strip off the debugging symbols (after saving a copy of the kernel with
> debugging symbols, of course). The problem is that kernels I strip on a
> machine using a kernel built after Saturday's changes don't boot. They
> just hang forever with the little spinning cursor. Kernels stripped on the
> same machine running a kernel from before Saturday's changes work just
> fine.
I can confirm this.
> From what I can tell, there are three bytes different between the
> two kernels:
>
> $ ls -la kernel*
> -rwxr-xr-x 1 ken wheel 1409956 Mar 10 09:50 kernel*
> -rwx------ 1 ken wheel 1409956 Mar 10 09:53 kernel.debug*
> $ cmp -l kernel kernel.debug
> 17 140 20
> 18 266 133
> 19 67 1
Those are in the a.out header in the field that says how many bytes
of symbol table are present. I noticed that in the failing case,
the header of the stripped kernel still says it has the same number
of bytes of symbols as the header of the unstripped kernel it was
made from. In other words, this statement at strip.c:241 isn't
taking effect:
/* Fill in new symbol table size. */
ep->a_syms = (nsym - symbase) * sizeof(NLIST);
Here, ep points to an image of the file that was mmapped at line 189:
/* Map the file. */
if ((ep = (EXEC *)mmap(NULL, (size_t)sb.st_size,
PROT_READ | PROT_WRITE, MAP_SHARED, fd, (off_t)0)) == (EXEC *)MAP_FAILED) {
--
John Polstra jdp@polstra.com
John D. Polstra & Co., Inc. Seattle, Washington USA
"Self-knowledge is always bad news." -- John Barth
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