__attribute_used__ error on 2.6.23.9

Hi,

I've been trying to modify the UML makefiles in the 2.6.23.9 kernel to compile against a different C library, but I'm running into trouble getting parts of UML to compile with GCC 4.2.1. In particular, files in os-Linux that use functions like __uml_setup are causing GCC to throw errors.

For example, when I try to compile arch/um/os-Linux/aio.c in my environment, I get the following:

gcc-4.2.1-rev -Wp,-MD,arch/um/os-Linux/.aio.o.d -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -Werror-implicit-function-declaration -Os -D__arch_um__ -DSUBARCH=\"i386\" -Dvmap=kernel_vmap -Din6addr_loopback=kernel_in6addr_loopback -Din6addr_any=kernel_in6addr_any -march=i686 -mpreferred-stack-boundary=2 -ffreestanding -D_LARGEFILE64_SOURCE -fno-unit-at-a-time -fno-omit-frame-pointer -fno-optimize-sibling-calls -g -fno-stack-protector -Wdeclaration-after-statement -Wno-pointer-sign -Iarch/um/include -I/home/tmjackso/build/orchestra/uml/linux-2.6.23.9/arch/um/include/skas -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -D_LARGEFILE64_SOURCE -DHAVE_AIO_ABI -v -nostdinc -I../../dietlibc/trunk/include -isystem /usr/local/gcc-4.2.1-rev/include -c -o arch/um/os-Linux/aio.o arch/um/os-Linux/aio.c
arch/um/os-Linux/aio.c:307: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘__attribute_used__’ arch/um/os-Linux/aio.c:307: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘__attribute_used__’ arch/um/os-Linux/aio.c:350: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘__attribute_used__’ arch/um/os-Linux/aio.c:360: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘__attribute_used__’

I know that __uml_setup and friends are defined in arch/um/include/init.h and it is being included, but it seems like GCC is not using it. If I comment out __uml_setup, other files which have functions starting with two underscores like __uml_initcall also cause compilation to fail.

Can anyone give some hints to solve this problem?

Cheers,

Todd Jackson

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Probably you need the patch below.

Jeff

Work email - jdike at linux dot intel dot com

From: Jeff Dike <[email protected]>

init.h started breaking now for some reason.  It turns out that there wasn't a
definition of __used.  Fixed this by copying the relevant stuff from
compiler.h in the userspace case, and including compiler.h in the kernel case.

Signed-off-by: Jeff Dike <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 arch/um/include/init.h |    9 +++++++++
 1 file changed, 9 insertions(+)

diff -puN arch/um/include/init.h~uml-arch-um-include-inith-needs-a-definition-of-__used arch/um/include/init.h
--- a/arch/um/include/init.h~uml-arch-um-include-inith-needs-a-definition-of-__used
+++ a/arch/um/include/init.h
@@ -40,6 +40,15 @@
 typedef int (*initcall_t)(void);
 typedef void (*exitcall_t)(void);
 
+#ifndef __KERNEL__
+#if __GNUC_MINOR__ >= 3
+# define __used			__attribute__((__used__))
+#else
+# define __used			__attribute__((__unused__))
+#endif
+#else
+#include <linux/compiler.h>
+#endif
 /* These are for everybody (although not all archs will actually
    discard it in modules) */
 #define __init		__attribute__ ((__section__ (".init.text")))
_

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Hi Jeff,

That patch didn't work...I'm still seeing the same error with the patch applied.

Is there anything glibc-specific that UML depends on?

Cheers,

Todd

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I would double-check that the patch is applied - I swear I saw some similar error which that fixed.

Not that I know of.

You're seeing a syntax error, so just make arch/um/os-Linux/aio.i, eyeball the result, and see what the used stuff is expanding into. That should give you an idea what needs to be done.

Jeff

Work email - jdike at linux dot intel dot com

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Can you make aio.i and send it to me?

Jeff

Work email - jdike at linux dot intel dot com

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