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    SubjectRe: __attribute__((unused))
    On Thu, Oct 14, 2004 at 11:04:56PM +0100, David Woodhouse wrote:
    > On Thu, 2004-10-14 at 22:02 +0100, Russell King wrote:
    > > Hi,
    > >
    > > I notice that module.h contains stuff like:
    > >
    > > #define MODULE_GENERIC_TABLE(gtype,name) \
    > > extern const struct gtype##_id __mod_##gtype##_table \
    > > __attribute__ ((unused, alias(__stringify(name))))
    > >
    > > and even:
    > >
    > > #define __MODULE_INFO(tag, name, info) \
    > > static const char __module_cat(name,__LINE__)[] \
    > > __attribute_used__ \
    > > __attribute__((section(".modinfo"),unused)) = __stringify(tag) "=" info
    > >
    > > My understanding is that we shouldn't be using __attribute__((unused))
    > > in either of these - can someone confirm.
    >
    > Since the structure in question isn't explicitly referenced from
    > elsewhere, the compiler may feel free to omit it. Since we want the
    > compiler to emit it, not omit it, we use "unused" to say "yes, I know it
    > looks unused; please emit it anyway". Later compilers use "used" to say
    > "I use it really; please emit it anyway", meaning much the same thing.

    It's the "later compilers" which I'm worried about here - I think they
    defined "unused" to mean "this really really isn't used and you can
    discard it". Hence my concern with the above.

    --
    Russell King
    Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
    maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
    2.6 Serial core
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