Re: Testing of function/data-sections on linux-2.6.35-rc4

Sam Ravnborg
2010-07-23T20:29:49Z

> * fix for module linker script: linux-2.6.35-rc4-fs.fix-ko-module-linker-script.patch
> Prevents kernel modules from having unnecessarily many
> sections and thus prevents module size growth.

Acked-by: Sam Ravnborg <sam@ravnborg.org>

--- linux-2.6.35-rc4/scripts/module-common.lds
+++ linux-2.6.35-rc4.new/scripts/module-common.lds
@@ -3,6 +3,29 @@
* Archs are free to supply their own linker scripts. ld will
* combine them automatically.
*/
+
+/* .data.foo are generated by gcc itself with -fdata-sections,
+ * whereas double-dot sections (like .data..percpu) are generated
+ * by kernel's magic macros.
+ *
+ * Since this script does not specify what to do with double-dot sections,
+ * ld -r will coalesce all .data..foo input sections into one .data..foo
+ * output section, all .data..bar input sections into one .data..bar
+ * output section and so on. This is exactly what we want.
+ *
+ * Same goes for .text, .bss and .rodata. In case of .rodata, various
+ * .rodata.foo sections are generated by gcc even without -fdata-sections
+ */
+
SECTIONS {
+
+ /* Coalesce sections produced by gcc -ffunction-sections */
+ .text 0 : AT(0) { *(.text .text.[A-Za-z0-9_$^]*) }
+
+ /* Coalesce sections produced by gcc -fdata-sections */
+ .rodata 0 : AT(0) { *(.rodata .rodata.[A-Za-z0-9_$^]*) }
+ .data 0 : AT(0) { *(.data .data.[A-Za-z0-9_$^]*) }
+ .bss 0 : AT(0) { *(.bss .bss.[A-Za-z0-9_$^]*) }
+
/DISCARD/ : { *(.discard) }
}