Re: [uml-devel] Re: [patch] module symbol fix

[BlaisorBlade <blaisorblade_spam@yahoo.it>]

Alle 10:26, venerdì 27 febbraio 2004, Gerd Knorr ha scritto:
> On Thu, Feb 26, 2004 at 10:26:55PM +0100, Gerd Knorr wrote:
> >   Hi,
> >
> > recent gcc versions need this one ...
>
> Another one of this kind (without this gcc may optimizes away the static
> declared but unreferenced stuff, resulting in initrd= and --help options
> not working any more for example ...).

Yes, but it needs to be made work with older gcc, even 2.95.3 but also 3.2 - 
and this means using __attribute__(__unused__) if needed - i.e. using 
__attribute__used as in the first patch (using more than one attribute works, 
as in include/linux/init.h).

The problem is that init.h is included even in userspace modules so it cannot 
include kernel headers - also, it seems that user_syms.c does not include 
<linux/compiler.h> and so __attribute_used cannot be expanded simply. If it 
works on you, check if the define comes from /usr/include/linux/compiler.h.

Duplicating the version check from include/linux/compiler* will be needed to 
avoid the problems you pointed out and possibly others, but not being able to 
include linux/* in user-objs is increasingly sucking. Sadly there are reasons 
for this and they are good (I discovered this while trying to remove this 
limitation):

- user space headers include /usr/include/linux/*, so if you add -I<source 
tree root>/include, those headers will include _other_ linux headers and 
things will not work - especially, they will include <source tree 
root>/include/asm-um/* instead of /usr/include/asm/*.

- definitions depending on CONFIG_* would be messed up; in fact, uml-config.h 
is a translation of config.h which defines UML_CONFIG_* instead of CONFIG_*, 
because CONFIG_* macros are defined by /usr/include/linux/autoconf.h. So if 
an "user-objs" file includes linux/mm.h, that header could even think that 
CONFIG_HIGHMEM is defined because the distro said so!
-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729



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