Messages in this thread |  | | | Date | Tue, 03 Nov 2009 12:16:24 +0000 | | From | Alan Jenkins <> | | Subject | Re: [PATCH 04/10] module: make MODULE_SYMBOL_PREFIX into a CONFIG option |
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Mike Frysinger wrote: > On Tue, Nov 3, 2009 at 05:06, Alan Jenkins wrote: > >> The next commit will require the use of MODULE_SYMBOL_PREFIX in >> .tmp_exports-asm.S. Currently it is mixed in with C structure >> definitions in "asm/module.h". Move the definition of this arch option >> into Kconfig, so it can be easily accessed by any code. >> >> This also lets modpost.c use the same definition. Previously modpost >> relied on a hardcoded list of architectures in mk_elfconfig.c. >> > > this should also let us push VMLINUX_SYMBOL() out of > arch/*/kernel/vmlinux.lds.S and into asm-generic/vmlinux.lds.h ... > > >> A build test for blackfin, one of the two MODULE_SYMBOL_PREFIX archs, >> showed the generated code was unchanged. vmlinux was identical save >> for build ids, and an apparently randomized suffix on a single "__key" >> symbol in the kallsyms data). >> > > when you get localized (static) namespace collisions, the linker > automatically does that > > >> --- a/init/Kconfig >> +++ b/init/Kconfig >> @@ -1171,6 +1171,17 @@ config MODULE_SRCVERSION_ALL >> >> endif # MODULES >> >> +config HAVE_SYMBOL_PREFIX >> + bool >> + help >> + Some arch toolchains use a `_' prefix for all user symbols. >> + This option will be taken into account when loading modules. >> + >> +config SYMBOL_PREFIX >> + string >> + default "_" if HAVE_SYMBOL_PREFIX >> + default "" >> > > in practice, the symbol prefix is an underscore. but there is no > technical limitation here -- the toolchain could use whatever prefix > they wanted > > so if the Kconfig option was pushed to arch/*/Kconfig, we could drop > HAVE_SYMBOL_PREFIX and let the arch declare the exact SYMBOL_PREFIX > value itself > -mike >
I don't think that's possible.
#define VMLINUX_SYMBOL(_sym_) _##_sym_
I don't know any "unstringify" operation. So I can't convert a string value of CONFIG_SYMBOL_PREFIX to the unquoted underscore we neeed for this macro. The same applies for the SYM() macro I use. Currently it assumes the prefix is a single underscore:
#ifdef HAVE_SYMBOL_PREFIX #define __SYM(sym) _##sym #else #define __SYM(sym) sym #endif
If we positively want to keep the generality, I guess I should put MODULE_SYMBOL_PREFIX in a header file of it's own. The disadvantage is that it makes it inaccessible to host programs again, like modpost (which currently hardcodes the list of affected architectures in mk_elfconfig.c).
Personally I favour "look, a small cleanup!" against "who knows what crazy things the next toolchain will do". Of course I'm open to being outvoted by experience :).
Regards Alan
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