On Wed, 2010-09-29 at 16:42 +0100, Russell King - ARM Linux wrote:

On Thu, Jul 08, 2010 at 11:16:45PM +0200, Linus Walleij wrote:

quoted

I'm especially in the dark about the usage of the L_PTE_* stuff,
and when to use DOMAIN_KERNEL, DOMAIN_USER and DOMAIN_IO. For
example: does DOMAIN_KERNEL imply kernel usage? DOMAIN_KERNEL
for ITCM makes the code non-executable. Does DOMAIN_USER imply
that L_PTE_USER shall also be set?

Sorry, should've replied to this much earlier.  We now have a problem in
that this stuff for the ITCM entry is wrong (identified via Santosh's
MT_MEMORY problems).

L_PTE_* define what ends up in the PTE entries.  L_PTE_USER and
L_PTE_WRITE operate together:

- None set, page is read-only in SVC mode, inaccessible in user mode.
- L_PTE_WRITE, page is read-write in SVC mode, inaccessible in user mode.
- L_PTE_USER, page is read-write in SVC mode, read-only in user mode.

Just a small addition - with the domains removal patch on ARMv7, this
becomes read-only for both SVC and user modes.

-- 
Catalin