[PATCH 11/12] kexec: allow architectures to override boot mapping
Russell King - ARM Linux
linux at arm.linux.org.uk
Fri Apr 29 11:08:28 PDT 2016
On Fri, Apr 29, 2016 at 08:44:29PM +0530, Pratyush Anand wrote:
> On Thu, Apr 28, 2016 at 2:58 PM, Russell King
> <rmk+kernel at arm.linux.org.uk> wrote:
> > kexec physical addresses are the boot-time view of the system. For
> > certain ARM systems (such as Keystone 2), the boot view of the system
> > does not match the kernel's view of the system: the boot view uses a
> > special alias in the lower 4GB of the physical address space.
> > To cater for these kinds of setups, we need to translate between the
> > boot view physical addresses and the normal kernel view physical
> > addresses. This patch extracts the current transation points into
> > linux/kexec.h, and allows an architecture to override the functions.
> > Due to the translations required, we unfortunately end up with six
> > translation functions, which are reduced down to four that the
> > architecture can override.
> > Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
> I must be missing something when I am thinking that, had we passed
> arch_phys_to_idmap_offset to user space, this patch would not have
> been needed, and things would have been more simpler. Please help me
> to understand why passing arch_phys_to_idmap_offset to user space
> would not be a good idea.
Sorry, I disagree.
Even if we thought that passing the offset to userspace would be a
good idea, it does nothing to solve each site in this patch. This
patch would still be necessary.
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
More information about the kexec