add an optional config option for stripping all unnecessary symbol exports from the...

SVN-Revision: 17181

diff --git a/Config.in b/Config.in
index 9879c7d9c099b5bb0418f3ee4867164be31e6db9..40764790219127af606449d8a861722899bc1300 100644 (file)
--- a/Config.in
+++ b/Config.in
@@ -134,6 +134,14 @@ config USE_MKLIBS
          Note that this will make the system libraries incompatible with most of the packages
          that are not selected during the build process
 
          Note that this will make the system libraries incompatible with most of the packages
          that are not selected during the build process
 

+config STRIP_KERNEL_EXPORTS
+       depends LINUX_2_6
+       bool "Strip unnecessary exports from the kernel image"
+       help
+         Reduces kernel size by stripping unused kernel exports from the kernel image
+         Note that this might make the kernel incompatible with any kernel modules that
+         were not selected at the time the kernel image was created
+

 comment "Package build options"
 
 config DEBUG
 comment "Package build options"
 
 config DEBUG

diff --git a/include/kernel-build.mk b/include/kernel-build.mk
index d48f8b9f53c8255d98767a7f92eadf97a0f7a1f9..e3e446ba584c17abb6e7d713fc22b413a28d873d 100644 (file)
--- a/include/kernel-build.mk
+++ b/include/kernel-build.mk
@@ -54,6 +54,28 @@ define BuildKernel
        $(Kernel/Prepare)
        touch $$@
 
        $(Kernel/Prepare)
        touch $$@
 

+  $(KERNEL_BUILD_DIR)/symtab.txt: FORCE
+       find $(LINUX_DIR) $(STAGING_DIR_ROOT)/lib/modules -name \*.ko | \
+               xargs $(TARGET_CROSS)nm | \
+               awk '$$$$1 == "U" { print $$$$2 } ' | \
+               sort -u > $$@
+
+  $(KERNEL_BUILD_DIR)/symtab.h: $(KERNEL_BUILD_DIR)/symtab.txt
+       ( \
+               echo '#define SYMTAB_KEEP \'; \
+               cat $(KERNEL_BUILD_DIR)/symtab.txt | \
+                       awk '{print "*(__ksymtab." $$$$1 ") \\" }'; \
+               echo; \
+               echo '#define SYMTAB_KEEP_GPL \'; \
+               cat $(KERNEL_BUILD_DIR)/symtab.txt | \
+                       awk '{print "*(__ksymtab_gpl." $$$$1 ") \\" }'; \
+               echo; \
+               echo '#define SYMTAB_KEEP_STR \'; \
+               cat $(KERNEL_BUILD_DIR)/symtab.txt | \
+                       awk '{print "*(__ksymtab_strings." $$$$1 ") \\" }'; \
+               echo; \
+       ) > $$@
+

   $(STAMP_CONFIGURED): $(STAMP_PREPARED) $(LINUX_CONFIG) $(GENERIC_LINUX_CONFIG) $(TOPDIR)/.config
        $(Kernel/Configure)
        touch $$@
   $(STAMP_CONFIGURED): $(STAMP_PREPARED) $(LINUX_CONFIG) $(GENERIC_LINUX_CONFIG) $(TOPDIR)/.config
        $(Kernel/Configure)
        touch $$@


@@ -62,7 +84,7 @@ define BuildKernel
        $(Kernel/CompileModules)
        touch $$@
 
        $(Kernel/CompileModules)
        touch $$@
 

-  $(LINUX_DIR)/.image: $(STAMP_CONFIGURED) FORCE
+  $(LINUX_DIR)/.image: $(STAMP_CONFIGURED) $(if $(CONFIG_STRIP_KERNEL_EXPORTS),$(KERNEL_BUILD_DIR)/symtab.h) FORCE

        $(Kernel/CompileImage)
        touch $$@
        
        $(Kernel/CompileImage)
        touch $$@
        

diff --git a/include/kernel-defaults.mk b/include/kernel-defaults.mk
index f2055535871f98393d773626f8aed8612253bafa..0ba1e056a69a30c5c626e66d6e66d6190aeaac8b 100644 (file)
--- a/include/kernel-defaults.mk
+++ b/include/kernel-defaults.mk
@@ -22,6 +22,11 @@ KERNEL_MAKEOPTS := -C $(LINUX_DIR) \
        KBUILD_HAVE_NLS=no \
        CONFIG_SHELL="$(BASH)"
 
        KBUILD_HAVE_NLS=no \
        CONFIG_SHELL="$(BASH)"
 

+ifdef CONFIG_STRIP_KERNEL_EXPORTS
+  KERNEL_MAKEOPTS += \
+       EXTRA_LDSFLAGS="-I$(KERNEL_BUILD_DIR) -include symtab.h"
+endif
+

 INITRAMFS_EXTRA_FILES ?= $(GENERIC_PLATFORM_DIR)/image/initramfs-base-files.txt
 
 ifneq (,$(KERNEL_CC))
 INITRAMFS_EXTRA_FILES ?= $(GENERIC_PLATFORM_DIR)/image/initramfs-base-files.txt
 
 ifneq (,$(KERNEL_CC))

diff --git a/target/linux/generic-2.6/patches-2.6.28/027-module_exports.patch b/target/linux/generic-2.6/patches-2.6.28/027-module_exports.patch
new file mode 100644 (file)
index 0000000..2a44832
--- /dev/null
+++ b/target/linux/generic-2.6/patches-2.6.28/027-module_exports.patch
@@ -0,0 +1,117 @@
+--- a/Makefile
++++ b/Makefile
+@@ -963,7 +963,7 @@ prepare: prepare0
+ # Leave this as default for preprocessing vmlinux.lds.S, which is now
+ # done in arch/$(ARCH)/kernel/Makefile
+ 
+-export CPPFLAGS_vmlinux.lds += -P -C -U$(ARCH)
++export CPPFLAGS_vmlinux.lds += -P -C -U$(ARCH) $(EXTRA_LDSFLAGS)
+ 
+ # The asm symlink changes when $(ARCH) changes.
+ # Detect this and ask user to run make mrproper
+--- a/include/asm-generic/vmlinux.lds.h
++++ b/include/asm-generic/vmlinux.lds.h
+@@ -2,6 +2,18 @@
+ #define LOAD_OFFSET 0
+ #endif
+ 
++#ifndef SYMTAB_KEEP_STR
++#define SYMTAB_KEEP_STR *(__ksymtab_strings.*)
++#endif
++
++#ifndef SYMTAB_KEEP
++#define SYMTAB_KEEP *(__ksymtab.*)
++#endif
++
++#ifndef SYMTAB_KEEP_GPL
++#define SYMTAB_KEEP_GPL *(__ksymtab_gpl.*)
++#endif
++
+ #ifndef VMLINUX_SYMBOL
+ #define VMLINUX_SYMBOL(_sym_) _sym_
+ #endif
+@@ -124,35 +136,35 @@
+       /* Kernel symbol table: Normal symbols */                       \
+       __ksymtab         : AT(ADDR(__ksymtab) - LOAD_OFFSET) {         \
+               VMLINUX_SYMBOL(__start___ksymtab) = .;                  \
+-              *(__ksymtab)                                            \
++              SYMTAB_KEEP                                             \
+               VMLINUX_SYMBOL(__stop___ksymtab) = .;                   \
+       }                                                               \
+                                                                       \
+       /* Kernel symbol table: GPL-only symbols */                     \
+       __ksymtab_gpl     : AT(ADDR(__ksymtab_gpl) - LOAD_OFFSET) {     \
+               VMLINUX_SYMBOL(__start___ksymtab_gpl) = .;              \
+-              *(__ksymtab_gpl)                                        \
++              SYMTAB_KEEP_GPL                                         \
+               VMLINUX_SYMBOL(__stop___ksymtab_gpl) = .;               \
+       }                                                               \
+                                                                       \
+       /* Kernel symbol table: Normal unused symbols */                \
+       __ksymtab_unused  : AT(ADDR(__ksymtab_unused) - LOAD_OFFSET) {  \
+               VMLINUX_SYMBOL(__start___ksymtab_unused) = .;           \
+-              *(__ksymtab_unused)                                     \
++              *(__ksymtab_unused.*)                                   \
+               VMLINUX_SYMBOL(__stop___ksymtab_unused) = .;            \
+       }                                                               \
+                                                                       \
+       /* Kernel symbol table: GPL-only unused symbols */              \
+       __ksymtab_unused_gpl : AT(ADDR(__ksymtab_unused_gpl) - LOAD_OFFSET) { \
+               VMLINUX_SYMBOL(__start___ksymtab_unused_gpl) = .;       \
+-              *(__ksymtab_unused_gpl)                                 \
++              *(__ksymtab_unused_gpl.*)                               \
+               VMLINUX_SYMBOL(__stop___ksymtab_unused_gpl) = .;        \
+       }                                                               \
+                                                                       \
+       /* Kernel symbol table: GPL-future-only symbols */              \
+       __ksymtab_gpl_future : AT(ADDR(__ksymtab_gpl_future) - LOAD_OFFSET) { \
+               VMLINUX_SYMBOL(__start___ksymtab_gpl_future) = .;       \
+-              *(__ksymtab_gpl_future)                                 \
++              *(__ksymtab_gpl_future.*)                               \
+               VMLINUX_SYMBOL(__stop___ksymtab_gpl_future) = .;        \
+       }                                                               \
+                                                                       \
+@@ -193,7 +205,13 @@
+                                                                       \
+       /* Kernel symbol table: strings */                              \
+         __ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) {       \
+-              *(__ksymtab_strings)                                    \
++              SYMTAB_KEEP_STR                                         \
++      }                                                               \
++                                                                      \
++      /DISCARD/ : {                                                   \
++              *(__ksymtab.*)                                          \
++              *(__ksymtab_gpl.*)                                      \
++              *(__ksymtab_strings.*)                                  \
+       }                                                               \
+                                                                       \
+       /* __*init sections */                                          \
+--- a/include/linux/module.h
++++ b/include/linux/module.h
+@@ -187,16 +187,24 @@ void *__symbol_get_gpl(const char *symbo
+ #define __CRC_SYMBOL(sym, sec)
+ #endif
+ 
++#ifdef MODULE
++#define __EXPORT_SUFFIX(sym)
++#else
++#define __EXPORT_SUFFIX(sym) "." #sym
++#endif
++
+ /* For every exported symbol, place a struct in the __ksymtab section */
+ #define __EXPORT_SYMBOL(sym, sec)                             \
+       extern typeof(sym) sym;                                 \
+       __CRC_SYMBOL(sym, sec)                                  \
+       static const char __kstrtab_##sym[]                     \
+-      __attribute__((section("__ksymtab_strings"), aligned(1))) \
++      __attribute__((section("__ksymtab_strings"              \
++        __EXPORT_SUFFIX(sym)), aligned(1)))                   \
+       = MODULE_SYMBOL_PREFIX #sym;                            \
+       static const struct kernel_symbol __ksymtab_##sym       \
+       __used                                                  \
+-      __attribute__((section("__ksymtab" sec), unused))       \
++      __attribute__((section("__ksymtab" sec                  \
++        __EXPORT_SUFFIX(sym)), unused))                       \
+       = { (unsigned long)&sym, __kstrtab_##sym }
+ 
+ #define EXPORT_SYMBOL(sym)                                    \

diff --git a/target/linux/generic-2.6/patches-2.6.30/028-module_exports.patch b/target/linux/generic-2.6/patches-2.6.30/028-module_exports.patch
new file mode 100644 (file)
index 0000000..ec037b3
--- /dev/null
+++ b/target/linux/generic-2.6/patches-2.6.30/028-module_exports.patch
@@ -0,0 +1,117 @@
+--- a/include/asm-generic/vmlinux.lds.h
++++ b/include/asm-generic/vmlinux.lds.h
+@@ -4,6 +4,18 @@
+ #define LOAD_OFFSET 0
+ #endif
+ 
++#ifndef SYMTAB_KEEP_STR
++#define SYMTAB_KEEP_STR *(__ksymtab_strings.*)
++#endif
++
++#ifndef SYMTAB_KEEP
++#define SYMTAB_KEEP *(__ksymtab.*)
++#endif
++
++#ifndef SYMTAB_KEEP_GPL
++#define SYMTAB_KEEP_GPL *(__ksymtab_gpl.*)
++#endif
++
+ #ifndef VMLINUX_SYMBOL
+ #define VMLINUX_SYMBOL(_sym_) _sym_
+ #endif
+@@ -176,35 +188,35 @@
+       /* Kernel symbol table: Normal symbols */                       \
+       __ksymtab         : AT(ADDR(__ksymtab) - LOAD_OFFSET) {         \
+               VMLINUX_SYMBOL(__start___ksymtab) = .;                  \
+-              *(__ksymtab)                                            \
++              SYMTAB_KEEP                                             \
+               VMLINUX_SYMBOL(__stop___ksymtab) = .;                   \
+       }                                                               \
+                                                                       \
+       /* Kernel symbol table: GPL-only symbols */                     \
+       __ksymtab_gpl     : AT(ADDR(__ksymtab_gpl) - LOAD_OFFSET) {     \
+               VMLINUX_SYMBOL(__start___ksymtab_gpl) = .;              \
+-              *(__ksymtab_gpl)                                        \
++              SYMTAB_KEEP_GPL                                         \
+               VMLINUX_SYMBOL(__stop___ksymtab_gpl) = .;               \
+       }                                                               \
+                                                                       \
+       /* Kernel symbol table: Normal unused symbols */                \
+       __ksymtab_unused  : AT(ADDR(__ksymtab_unused) - LOAD_OFFSET) {  \
+               VMLINUX_SYMBOL(__start___ksymtab_unused) = .;           \
+-              *(__ksymtab_unused)                                     \
++              *(__ksymtab_unused.*)                                   \
+               VMLINUX_SYMBOL(__stop___ksymtab_unused) = .;            \
+       }                                                               \
+                                                                       \
+       /* Kernel symbol table: GPL-only unused symbols */              \
+       __ksymtab_unused_gpl : AT(ADDR(__ksymtab_unused_gpl) - LOAD_OFFSET) { \
+               VMLINUX_SYMBOL(__start___ksymtab_unused_gpl) = .;       \
+-              *(__ksymtab_unused_gpl)                                 \
++              *(__ksymtab_unused_gpl.*)                               \
+               VMLINUX_SYMBOL(__stop___ksymtab_unused_gpl) = .;        \
+       }                                                               \
+                                                                       \
+       /* Kernel symbol table: GPL-future-only symbols */              \
+       __ksymtab_gpl_future : AT(ADDR(__ksymtab_gpl_future) - LOAD_OFFSET) { \
+               VMLINUX_SYMBOL(__start___ksymtab_gpl_future) = .;       \
+-              *(__ksymtab_gpl_future)                                 \
++              *(__ksymtab_gpl_future.*)                               \
+               VMLINUX_SYMBOL(__stop___ksymtab_gpl_future) = .;        \
+       }                                                               \
+                                                                       \
+@@ -245,7 +257,13 @@
+                                                                       \
+       /* Kernel symbol table: strings */                              \
+         __ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) {       \
+-              *(__ksymtab_strings)                                    \
++              SYMTAB_KEEP_STR                                         \
++      }                                                               \
++                                                                      \
++      /DISCARD/ : {                                                   \
++              *(__ksymtab.*)                                          \
++              *(__ksymtab_gpl.*)                                      \
++              *(__ksymtab_strings.*)                                  \
+       }                                                               \
+                                                                       \
+       /* __*init sections */                                          \
+--- a/include/linux/module.h
++++ b/include/linux/module.h
+@@ -187,16 +187,24 @@ void *__symbol_get_gpl(const char *symbo
+ #define __CRC_SYMBOL(sym, sec)
+ #endif
+ 
++#ifdef MODULE
++#define __EXPORT_SUFFIX(sym)
++#else
++#define __EXPORT_SUFFIX(sym) "." #sym
++#endif
++
+ /* For every exported symbol, place a struct in the __ksymtab section */
+ #define __EXPORT_SYMBOL(sym, sec)                             \
+       extern typeof(sym) sym;                                 \
+       __CRC_SYMBOL(sym, sec)                                  \
+       static const char __kstrtab_##sym[]                     \
+-      __attribute__((section("__ksymtab_strings"), aligned(1))) \
++      __attribute__((section("__ksymtab_strings"              \
++        __EXPORT_SUFFIX(sym)), aligned(1)))                   \
+       = MODULE_SYMBOL_PREFIX #sym;                            \
+       static const struct kernel_symbol __ksymtab_##sym       \
+       __used                                                  \
+-      __attribute__((section("__ksymtab" sec), unused))       \
++      __attribute__((section("__ksymtab" sec                  \
++        __EXPORT_SUFFIX(sym)), unused))                       \
+       = { (unsigned long)&sym, __kstrtab_##sym }
+ 
+ #define EXPORT_SYMBOL(sym)                                    \
+--- a/Makefile
++++ b/Makefile
+@@ -994,7 +994,7 @@ prepare: prepare0
+ # Leave this as default for preprocessing vmlinux.lds.S, which is now
+ # done in arch/$(ARCH)/kernel/Makefile
+ 
+-export CPPFLAGS_vmlinux.lds += -P -C -U$(ARCH)
++export CPPFLAGS_vmlinux.lds += -P -C -U$(ARCH) $(EXTRA_LDSFLAGS)
+ 
+ # The asm symlink changes when $(ARCH) changes.
+ # Detect this and ask user to run make mrproper