Messages in this thread | | | Date | Thu, 26 Nov 2009 17:14:55 +0000 | From | Alan Jenkins <> | Subject | Re: [PATCH 05/10] kbuild: sort the list of symbols exported by the kernel (__ksymtab) |
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Andrew Morton wrote: > On Tue, 3 Nov 2009 10:06:17 +0000 > Alan Jenkins <alan-jenkins@tuffmail.co.uk> wrote: > > >> modpost of vmlinux.o now extracts the ksymtab sections and outputs >> sorted versions of them as .tmp_exports-asm.S. These sorted sections >> are linked into vmlinux and the original unsorted sections are >> discarded. >> >> This will allow modules to be loaded faster, resolving symbols using >> binary search, without any increase in the memory needed for the >> symbol tables. >> >> This does not affect the building of modules, so hopefully it won't >> affect compile times too much. >> >> Minimally tested on ARM under QEMU emulator. >> Build tested on blackfin; output of "size -A" unchanged. >> > > I'm getting a segfault from write_exports(). > > (gdb) bt > #0 0x0000003e5f075510 in strlen () from /lib64/libc.so.6 > #1 0x0000003e5f045cb8 in vfprintf () from /lib64/libc.so.6 > #2 0x0000003e5f06683a in vsnprintf () from /lib64/libc.so.6 > #3 0x0000000000401897 in buf_printf (buf=0x7fff5514f5e0, > fmt=0x7fff5514f4e0 "0x%02x ") at scripts/mod/modpost.c:1692 > #4 0x00000000004042c8 in main (argc=1024, argv=0x7fff5514f5e0) > at scripts/mod/modpost.c:2063 > (gdb) f 4 > #4 0x00000000004042c8 in main (argc=1024, argv=0x7fff5514f5e0) > at scripts/mod/modpost.c:2063 > 2063 buf_printf(&buf, "__EXPORT_%s_SYMBOL(%s," > (gdb) p sym > $1 = (struct symbol *) 0x65c9f0 > (gdb) p *sym > $2 = {next = 0x64c3a0, module = 0x610010, crc = 4077789248, crc_valid = 1, > weak = 0, vmlinux = 0, kernel = 0, preloaded = 0, function = 1, > export = export_unknown, name = 0x65ca10 "simple_prepare_write"} > (gdb) p sym->export > $3 = export_unknown > (gdb) p/d sym->export > $4 = 5 > > but section_names[] (which could be static in write_exports() btw) has > only five entries. >
Thanks. I can't work out why this would happen. Could you show the options modpost is being run with (make V=1 will do)? Also confirm whether this is "MODPOST vmlinux.o" or "MODPOST 1001 modules".
> main (argc=1024
It looks like this is the step "MODPOST 1001 modules". But that shouldn't run write_exports(). We only run modpost with "-x" for the step "MODPOST vmlinux.o". Also, the vmlinux-only modpost is run first, so I wonder why it didn't hit the same problem.
I don't know why sym->vmlinux==0 either; simple_prepare_write() should always be built into vmlinux. Perhaps modpost is being run on libfs.o for some strange reason.
Alan
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