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fls() not available in Linux 2.4

PATCH In review Wolfgang Grandegger 2 participants 5 messages Aug 16, 2007

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Wolfgang Grandegger

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#0 lore raw

PATCH 1/1 fls() not available in Linux 2.4

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.

asm-generic/wrappers.h +12 -0
Index: include/asm-generic/wrappers.h
===================================================================
@@ -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) \
#1 lore raw
Quoted 10 lines · Wolfgang Grandegger

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 ?

Signature · 1 line
					    Gilles Chanteperdrix.
author
#2 lore raw
Quoted 6 lines · Gilles Chanteperdrix
Quoted 5 lines · Wolfgang Grandegger

Hello,

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

Quoted 8 lines
Quoted 5 lines

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.

#3 lore raw
Quoted 13 lines · Wolfgang Grandegger
Quoted 12 lines · Gilles Chanteperdrix
Quoted 10 lines · Wolfgang Grandegger

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'

Quoted 6 lines
Quoted 2 lines

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.

Signature · 1 line
                                               Gilles Chanteperdrix
#4 lore raw
In reply to Wolfgang Grandegger
Quoted 10 lines · Wolfgang Grandegger

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.

Signature · 1 line
					    Gilles Chanteperdrix.