Re: Patch to reorder functions in the vmlinux to a defined order

[Arjan van de Ven]

On Thu, 2006-02-23 at 17:00 +0100, Andi Kleen wrote:
> On Thursday 23 February 2006 16:09, Arjan van de Ven wrote:
> 
> > This patch puts the infrastructure in place to allow for a reordering of
> > functions based inside the vmlinux. The general idea is that it is possible
> > to put all "common" functions into the first 2Mb of the code, so that they
> > are covered by one TLB entry. This as opposed to the current situation where
> > a typical vmlinux covers about 3.5Mb (on x86-64) and thus 2 TLB entries.
> > (This patch depends on the previous patch to pin head.S as first in the order)
> 
> I think you would first need to move the code first for that. Currently it starts
> at 1MB, which means 1MB is already wasted of the aligned 2MB TLB entry.
> 
> I wouldn't have a problem with moving the 64bit kernel to 2MB though.

that was easy since it's a Config entry already ;)


---


As suggested by Andi (and Alan), move the default kernel location
from 1Mb to 2Mb, to align to the start of a TLB entry.

Signed-off-by: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>

---
 arch/x86_64/Kconfig |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6.16-reorder/arch/x86_64/Kconfig
===================================================================
--- linux-2.6.16-reorder.orig/arch/x86_64/Kconfig
+++ linux-2.6.16-reorder/arch/x86_64/Kconfig
@@ -444,10 +444,10 @@ config CRASH_DUMP
 config PHYSICAL_START
 	hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
 	default "0x1000000" if CRASH_DUMP
-	default "0x100000"
+	default "0x200000"
 	help
 	  This gives the physical address where the kernel is loaded. Normally
-	  for regular kernels this value is 0x100000 (1MB). But in the case
+	  for regular kernels this value is 0x200000 (2MB). But in the case
 	  of kexec on panic the fail safe kernel needs to run at a different
 	  address than the panic-ed kernel. This option is used to set the load
 	  address for kernels used to capture crash dump on being kexec'ed

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