[Xenomai-core] [PATCH] fls() not available in Linux 2.4

[Xenomai-core] [PATCH] fls() not available in Linux 2.4

[Wolfgang Grandegger]

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Hello,

the attached patch fixes the following compilation error with Xenomai's 
head of trunk under Linux 2.4:

kernel/kernel.o(.text+0x135a4): In function `__rthal_generic_full_divmod64':
/temp/rtcan/devel/linuxppc_2_4_devel-xenomai/kernel/xenomai/arch/generic/hal.c:918: 
undefined reference to `fls'
kernel/kernel.o(.text+0x135b4):/temp/rtcan/devel/linuxppc_2_4_devel-xenomai/kernel/xenomai/arch/generic/hal.c:918: 
undefined reference to `fls'

Wolfgang.

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Index: include/asm-generic/wrappers.h
===================================================================
--- include/asm-generic/wrappers.h	(revision 2922)
+++ include/asm-generic/wrappers.h	(working copy)
@@ -183,6 +183,18 @@ void show_stack(struct task_struct *task
 #define __deprecated  __attribute__((deprecated))
 #endif
 
+/*
+ * fls: find last (most-significant) bit set.
+ * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
+ */
+static __inline__ int fls(unsigned int x)
+{
+        int lz;
+
+        asm ("cntlzw %0,%1" : "=r" (lz) : "r" (x));
+        return 32 - lz;
+}
+
 #else /* LINUX_VERSION_CODE >= KERNEL_VERSION(2,5,0) */
 
 #define compat_module_param_array(name, type, count, perm) \

Re: [Xenomai-core] [PATCH] fls() not available in Linux 2.4

[Gilles Chanteperdrix]

Wolfgang Grandegger wrote:
 > Hello,
 > 
 > the attached patch fixes the following compilation error with Xenomai's 
 > head of trunk under Linux 2.4:
 > 
 > kernel/kernel.o(.text+0x135a4): In function `__rthal_generic_full_divmod64':
 > /temp/rtcan/devel/linuxppc_2_4_devel-xenomai/kernel/xenomai/arch/generic/hal.c:918: 
 > undefined reference to `fls'
 > kernel/kernel.o(.text+0x135b4):/temp/rtcan/devel/linuxppc_2_4_devel-xenomai/kernel/xenomai/arch/generic/hal.c:918: 
 > undefined reference to `fls'

Should not this implementation go to asm-powerpc/wrappers.h instead of
asm-generic/wrappers.h ?

-- 


					    Gilles Chanteperdrix.

Re: [Xenomai-core] [PATCH] fls() not available in Linux 2.4

[Wolfgang Grandegger]

Gilles Chanteperdrix wrote:
> Wolfgang Grandegger wrote:
>  > Hello,
>  > 
>  > the attached patch fixes the following compilation error with Xenomai's 
>  > head of trunk under Linux 2.4:
>  > 
>  > kernel/kernel.o(.text+0x135a4): In function `__rthal_generic_full_divmod64':
>  > /temp/rtcan/devel/linuxppc_2_4_devel-xenomai/kernel/xenomai/arch/generic/hal.c:918: 
>  > undefined reference to `fls'
>  > kernel/kernel.o(.text+0x135b4):/temp/rtcan/devel/linuxppc_2_4_devel-xenomai/kernel/xenomai/arch/generic/hal.c:918: 
>  > undefined reference to `fls'
> 
> Should not this implementation go to asm-powerpc/wrappers.h instead of
> asm-generic/wrappers.h ?

Ah, yes, of course, because it uses PowerPC assembler. But it might be 
missing for other archs as well, e.g. I did not find it for i386 in the 
DENX Linux 2.4.25 tree.

Wolfgang.

Re: [Xenomai-core] [PATCH] fls() not available in Linux 2.4

[Gilles Chanteperdrix]

On 8/16/07, Wolfgang Grandegger <wg@domain.hid> wrote:
> Gilles Chanteperdrix wrote:
> > Wolfgang Grandegger wrote:
> >  > Hello,
> >  >
> >  > the attached patch fixes the following compilation error with Xenomai's
> >  > head of trunk under Linux 2.4:
> >  >
> >  > kernel/kernel.o(.text+0x135a4): In function `__rthal_generic_full_divmod64':
> >  > /temp/rtcan/devel/linuxppc_2_4_devel-xenomai/kernel/xenomai/arch/generic/hal.c:918:
> >  > undefined reference to `fls'
> >  > kernel/kernel.o(.text+0x135b4):/temp/rtcan/devel/linuxppc_2_4_devel-xenomai/kernel/xenomai/arch/generic/hal.c:918:
> >  > undefined reference to `fls'
> >
> > Should not this implementation go to asm-powerpc/wrappers.h instead of
> > asm-generic/wrappers.h ?
>
> Ah, yes, of course, because it uses PowerPC assembler. But it might be
> missing for other archs as well, e.g. I did not find it for i386 in the
> DENX Linux 2.4.25 tree.

We will add it to asm-i386/wrappers.h as well then.

-- 
                                               Gilles Chanteperdrix

Re: [Xenomai-core] [PATCH] fls() not available in Linux 2.4

[Gilles Chanteperdrix]

Wolfgang Grandegger wrote:
 > Hello,
 > 
 > the attached patch fixes the following compilation error with Xenomai's 
 > head of trunk under Linux 2.4:
 > 
 > kernel/kernel.o(.text+0x135a4): In function `__rthal_generic_full_divmod64':
 > /temp/rtcan/devel/linuxppc_2_4_devel-xenomai/kernel/xenomai/arch/generic/hal.c:918: 
 > undefined reference to `fls'
 > kernel/kernel.o(.text+0x135b4):/temp/rtcan/devel/linuxppc_2_4_devel-xenomai/kernel/xenomai/arch/generic/hal.c:918: 
 > undefined reference to `fls'

Should be fixed now, thanks.

-- 


					    Gilles Chanteperdrix.