sh: inconsistent kallsyms data

Paul Mundt
2004-12-31T17:26:02Z

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Building 2.6.10 for sh results in inconsistent kallsyms data. Turning on
CONFIG_KALLSYMS_ALL fixes it, as does CONFIG_KALLSYMS_EXTRA_PASS.

The symbols that seem to be problematic between the second and third
pass are all kallsyms special symbols. With only CONFIG_KALLSYMS set we
see:

--- System.map 2004-12-31 10:53:10.278567522 -0600
+++ .tmp_System.map 2004-12-31 10:53:10.347558024 -0600
@@ -6868,9 +6868,9 @@
8817c4d0 D kallsyms_addresses
88182660 D kallsyms_num_syms
88182670 D kallsyms_names
-88190630 D kallsyms_markers
-881906a0 D kallsyms_token_table
-88190b50 D kallsyms_token_index
+881906a0 D kallsyms_markers
+88190710 D kallsyms_token_table
+88190bc0 D kallsyms_token_index
88191000 D irq_desc
88191000 A __per_cpu_end
88191000 A __per_cpu_start

So for some reason we have a 0x70 variance between these, and only
these. Running with --all-symbols this seems to work fine.

Looking at scripts/kallsyms.c:symbol_valid, we see:

/* Symbols which vary between passes. Passes 1 and 2 must have
* identical symbol lists. The kallsyms_* symbols below are only added
* after pass 1, they would be included in pass 2 when --all-symbols is
* specified so exclude them to get a stable symbol list.
*/

Going by this it's not entirely clear if there is a problem or not. If
these symbols are supposed to be excluded due to being "special", then
it doesn't seem like verify_kallsyms in the top-level Makefile is doing
the right thing by just doing a blind cmp -s. This comment also seems to
be a bit outdated or just generally inaccurate, as --all-symbols isn't
the default behaviour unless CONFIG_KALLSYMS_ALL is set.

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