Extraversion in System.map?

As part of my penance for using the wrong System.map file in the readprofile data I sent out, I have prepared a patch to readprofile that makes it check the version of the file against the kernel.

Much to my dismay, the extraversion code ('-pre6' for example) does not appear to be anywhere in System.map. Or am I wrong? If not, why not, and can this be fixed? After all, symbols can and do change between -pre versions.

Dr. Tom Holroyd
"I am, as I said, inspired by the biological phenomena in which chemical forces are used in repetitious fashion to produce all kinds of weird effects (one of which is the author)."
-- Richard Feynman, _There's Plenty of Room at the Bottom_

Eh, no kernel version is associated with System.map. It has no embedded information, what-so-ever, aside from the symbols.

Do what everyone else does and name your System.map appropriately, i.e. System.map-2.5.8-pre2 and then on boot symlink System.map to System.map-uname -r. Most (all?) distributions do this for you already.

You can also pass readprofile the -m flag to specify the map file to use. A little script that does "readprofile -m System.map-uname -r" would work fine.

Robert Love

System.map only contains the numeric kernel version. After all, it is difficult to convert 2.4.19-pre6 to Version_132115-pre6 when symbols cannot contain '-'.

Don't reinvent the wheel, use ksymoops -s save.map. ksymoops has all the verification code that I can think off, -s writes the merged map including module information.

Well, that has an obvious solution, but modifying the Version string would likely break something. Adding another string would work. It could even be done without making the kernel image bigger. In fact, the Version_* symbol (and Extraversion_* symbol) could both be made __initdata, couldn't they?

Now there's a clever idea.

Where the symbol's content is placed is irrelevant. System.map contains the symbol _name_, not its _contents_. But symbol names cannot contain the special characters that people put in extraversion. Even mapping the special characters to '_' will not help because a lot of people do not change extraversion when changing config and the change of config can really move symbols around. Hence all the checks that ksymoops does to validate symbol addresses between multiple sources.

I have some ideas about making System.map and the kernel record which build they refer to, including the .config data. But that is 2.5 material, after kbuild 2.5 goes in.

In article <1018246521.1534.145.camel@phantasy>,

Not even that is needed. Most if not all utilities that need a system.map file check for System.map-uname -r _first_ and only if that is not found fall back to plain System.map. So the symlink is superfluous.

Mike.