Date: Thu, 25 Nov 2010 21:10:34 +0100 From: Erik Cederstrand <erik@cederstrand.dk> To: Mark Johnston <markjdb@gmail.com> Cc: FreeBSD Hackers <hackers@FreeBSD.org> Subject: Re: Deterministic builds, part 2 Message-ID: <0B04A57E-A325-4006-8A01-6C7F15584C2F@cederstrand.dk> In-Reply-To: <20101125191727.GB1342@mark-laptop-bsd.mark-home> References: <93FA0AC7-704D-4EB4-A163-FDD8AC915630@cederstrand.dk> <20101125191727.GB1342@mark-laptop-bsd.mark-home>
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Den 25/11/2010 kl. 20.17 skrev Mark Johnston: > On Thu, Nov 25, 2010 at 01:08:58PM +0100, Erik Cederstrand wrote: >> Kernel modules: >> ---------------------- >> In the ELF section .gnu-debuglink, there is a link to the corresponding *.ko.symbols file. It seems to be an inode or such rather than a file path since nothing shows up in strings(1). I have commented out "makeoptions DEBUG=-g" in the GENERIC kernel conf file which I am testing now, but I'd like to know what is actually going on. > > The .gnu_debuglink segment contains the name of the debug symbols file > (i.e. not a full path or an inode number). I'm not sure why it doesn't > show up with strings(1), but you can see it with a hex editor. > > When gdb loads an object file with a gnu_debuglink segment, it looks in > a few pre-defined locations for the corresponding symbols file. The gdb > docs explain it pretty well: > > http://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html Thanks. I was explained in private email that I should be using "strings -a" which indeed turns up the filename. The checksum mismatch actually occurs because the section also contains a CRC of the symbols file, which means the symbols files aren't identical. I'll investigate that separately. Erik
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