Currently we can mark an initialized data to belong to the init.data
section, this data being discarded after the boot process and the
memory space used is taken back by the kernel. For _uninitialized_
data, we must use the same mechanism.
The main drawback of this is that these data take space in the kernel
image whereas this space is not really used. It's actually the reason
why we prefer to not initialize a normal data when its initial value
is 0.
This patch creates two new init sections called '.bss.init' and
'.bss.exit'.
These sections are similar to the .{init,exit}.data ones but doesn't
consume any space in the vmlinux image because they're part of the bss
section except that they're freed once the kernel has booted.
To select the BSS attribute for a peculiar section, the name of the
section must start with 'bss.' pattern. This is at least how GCC
3.2/4.1.2 works and it's the reason why the 2 new sections haven't
been called '.{init,exit}.bss'.
To mark a data part of one of these 2 sections, we use the 2 new
annotations: __initbss/__exitbss.
All data marked as part of this section must not be initialized,
of course.
Signed-off-by: Franck Bui-Huu <fbuihuu@xxxxxxxxx>
---
include/linux/init.h | 25 +++++++++++++++++--------
1 files changed, 17 insertions(+), 8 deletions(-)
diff --git a/include/linux/init.h b/include/linux/init.h
index 5141381..19e04b2 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -43,6 +43,8 @@
#define __init __attribute__ ((__section__ (".init.text"))) __cold
#define __initdata __attribute__ ((__section__ (".init.data")))
#define __exitdata __attribute__ ((__section__(".exit.data")))
+#define __initbss __attribute__ ((__section__ (".bss.init")))
+#define __exitbss __attribute__ ((__section__ (".bss.exit")))
#define __exit_call __attribute_used__ __attribute__ ((__section__ (".exitcall.exit")))
/* modpost check for section mismatches during the kernel build.
@@ -71,6 +73,7 @@
#define __FINIT .previous
#define __INITDATA .section ".init.data","aw"
#define __INITDATA_REFOK .section ".data.init.refok","aw"
+#define __INITBSS .section ".bss.init","aw",@nobits
#ifndef __ASSEMBLY__
/*
@@ -260,10 +263,12 @@ void __init parse_early_param(void);
#define __devexit
#define __devexitdata
#else
-#define __devinit __init
-#define __devinitdata __initdata
-#define __devexit __exit
-#define __devexitdata __exitdata
+#define __devinit __init
+#define __devinitdata __initdata
+#define __devinitbss __initbss
+#define __devexit __exit
+#define __devexitdata __exitdata
+#define __devexitbss __exitbss
#endif
#ifdef CONFIG_HOTPLUG_CPU
@@ -273,9 +278,11 @@ void __init parse_early_param(void);
#define __cpuexitdata
#else
#define __cpuinit __init
-#define __cpuinitdata __initdata
-#define __cpuexit __exit
+#define __cpuinitdata __initdata
+#define __cpuinitbss __initbss
+#define __cpuexit __exit
#define __cpuexitdata __exitdata
+#define __cpuexitbss __exitbss
#endif
#if defined(CONFIG_MEMORY_HOTPLUG) || defined(CONFIG_ACPI_HOTPLUG_MEMORY) \
@@ -286,9 +293,11 @@ void __init parse_early_param(void);
#define __memexitdata
#else
#define __meminit __init
-#define __meminitdata __initdata
-#define __memexit __exit
+#define __meminitdata __initdata
+#define __meminitbss __meminitbss
+#define __memexit __exit
#define __memexitdata __exitdata
+#define __memexitbss __exitbss
#endif
/* Functions marked as __devexit may be discarded at kernel link time, depending
--
1.5.3.5
