We found the problem when porting code from Linux 2.4 to 2.6, where a
user space application maps a 1 MByte region of DRAM with the O_SYNC
flag to communicate with an internal core that shares access to the
DRAM but does not have any cache snooping logic.
In 2.4 the mem driver honors the O_SYNC f
On Thu, 2008-05-08 at 00:17 -0700, Nick Spence wrote:
> The page protection seemed to be allocated on a per pte basis, where
> each PTE is a small fixed size. I will need to check the TLB setup
> further.
The problem is that it will then be part of the linear mapping, which
means you'll end up w
Benjamin Herrenschmidt wrote:
On Wed, 2008-05-07 at 23:31 -0700, Spence Nick wrote:
Then you should completely carve it out of the LMB's which will ensure
it's not seen as RAM by /dev/mem and not mapped by the linear mapping
(well, the later depends ... if it's carved out of the top of RAM it
sh
On Wed, 2008-05-07 at 23:31 -0700, Spence Nick wrote:
>
> In our case the memory area is reserved so that the main processor will
> not touch it except when mapped by the mem driver.
Then you should completely carve it out of the LMB's which will ensure
it's not seen as RAM by /dev/mem and not m
Paul Mackerras wrote:
> This says nothing about why you want to do this---what bad
> things arise from the present code, or what good things would
> happen if the change was made. It needs to.
We found the problem when porting code from Linux 2.4 to 2.6, where a
user space application maps a 1
[EMAIL PROTECTED] writes:
> This patch re-introduces the O_SYNC flag to make DRAM non-cached, which is
> the default behavior
> for non PowerPC architectures in /drivers/char/mem.c
This says nothing about why you want to do this---what bad things
arise from the present code, or what good things
From: Nick Spence <[EMAIL PROTECTED]>
This patch re-introduces the O_SYNC flag to make DRAM non-cached, which is the
default behavior
for non PowerPC architectures in /drivers/char/mem.c
Signed-off-by: Nick Spence <[EMAIL PROTECTED]>
---
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
