Hi Sam,

Thanks for the comments, will integrate in my next post. I noticed that
this version was against 2.6.21-mm2, not what I thought it was
(2.6.22-rc2-mm1).

Mathieu


* Sam Ravnborg (sam@ravnborg.org) wrote:

Hi Mathieu

quoted

Adds a place to declare rw data that will not be far from the .data content,
therefore limiting the impact on cache of data declared in sections part of the
EXTRA_RWDATA.

No comments on the aim of the path - but a few implementation comments.

I'm glad to see asm-generic/vmlinux.lds.h used - thanks.
The general naming is USAGE_{DATA|TEXT}
To keep with this albait vague then established naming scheme
please consider using: EXTRARW_DATA

quoted

Index: linux-2.6-lttng/arch/h8300/kernel/vmlinux.lds.S
===================================================================

--- linux-2.6-lttng.orig/arch/h8300/kernel/vmlinux.lds.S	2007-05-15 18:41:05.000000000 -0400
+++ linux-2.6-lttng/arch/h8300/kernel/vmlinux.lds.S	2007-05-15 18:44:20.000000000 -0400

@@ -105,7 +105,9 @@
 	. = ALIGN(0x4) ;
 		*(.data)
 	. = ALIGN(0x4) ;
-		*(.data.*)	
+		*(.data.*)
+	. = ALIGN(0x4) ;
+	EXTRA_RWDATA

The usage of ALIGN seems a bit arbitary. If there is a requirement to align
data for EXTRA_RWDATA usage then pass alignment requirment as parameter or do
alignment in the define.

quoted

Index: linux-2.6-lttng/arch/ia64/kernel/vmlinux.lds.S
===================================================================

--- linux-2.6-lttng.orig/arch/ia64/kernel/vmlinux.lds.S	2007-05-15 18:41:05.000000000 -0400
+++ linux-2.6-lttng/arch/ia64/kernel/vmlinux.lds.S	2007-05-15 18:44:20.000000000 -0400

@@ -214,7 +214,7 @@
 
   data : { } :data
   .data : AT(ADDR(.data) - LOAD_OFFSET)
-	{ *(.data) *(.data1) *(.gnu.linkonce.d*) CONSTRUCTORS }
+	{ *(.data) *(.data1) *(.gnu.linkonce.d*) EXTRA_RWDATA CONSTRUCTORS }
 

Try to think of linker scripts a C-files.
In C you would never do like this:

-	int i; struct type foo;
+	int i; struct type foo; struct type2 bar;

You would certainly place the new variable on a new line and maybe
fix the bad code-style in another patch.
My point is that you should not continue the bad-taste style used here
but just add EXTRA_RWDATA on a single line.

If no-one beats me I plan to go through all linker scrip files and add
some sanity with respect to indent style etc. so they start to follow
C-style for indent.

quoted

Index: linux-2.6-lttng/arch/xtensa/kernel/vmlinux.lds.S
===================================================================

--- linux-2.6-lttng.orig/arch/xtensa/kernel/vmlinux.lds.S	2007-05-15 18:41:05.000000000 -0400
+++ linux-2.6-lttng/arch/xtensa/kernel/vmlinux.lds.S	2007-05-15 18:44:20.000000000 -0400

@@ -144,7 +144,7 @@
   _fdata = .;
   .data :
   {
-    *(.data) CONSTRUCTORS
+    *(.data) EXTRA_RWDATA CONSTRUCTORS
     . = ALIGN(XCHAL_ICACHE_LINESIZE);
     *(.data.cacheline_aligned)

again..

quoted

   }
Index: linux-2.6-lttng/include/asm-generic/vmlinux.lds.h
===================================================================

--- linux-2.6-lttng.orig/include/asm-generic/vmlinux.lds.h	2007-05-15 18:44:11.000000000 -0400
+++ linux-2.6-lttng/include/asm-generic/vmlinux.lds.h	2007-05-15 18:44:20.000000000 -0400

@@ -143,6 +143,8 @@
 									\
 	. = ALIGN(4096);
 
+#define EXTRA_RWDATA
+

Please add comment that describe the purpose of EXTRA_RWDATA - verbatim
copy from changlog is almost enough.

	Sam

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68