Locking out AML code

Locking out AML code

[Hector Martin]

I'm writing a driver to access some EC-related functionality on some
Acer laptops. This uses a separate IO port interface and cannot be done
using the standard ec_read / ec_write ACPI functions. The DSDT also
accesses these IO ports for a few things (most notably display
brightness and some WMI methods). Is there a lock I can hold (from
outside the ACPI subsystem) that will lock out AML method execution
while I poke the hardware?

FWIW, the Windows drivers from Acer also access those IO ports directly
(from userspace, no less, with a dumb kernel driver to provide port I/O
to userspace and in the process introduce a huge security hole of
course). There is no way of talking to this hardware via DSDT methods.

-- 
Hector Martin (hector@marcansoft.com)
Public Key: http://www.marcansoft.com/marcan.asc

Re: Locking out AML code

[Lin Ming]

On Tue, Jul 7, 2009 at 10:08 PM, Hector Martin<hector@marcansoft.com> wrote:
> I'm writing a driver to access some EC-related functionality on some
> Acer laptops. This uses a separate IO port interface and cannot be done
> using the standard ec_read / ec_write ACPI functions. The DSDT also
> accesses these IO ports for a few things (most notably display
> brightness and some WMI methods). Is there a lock I can hold (from
> outside the ACPI subsystem) that will lock out AML method execution
> while I poke the hardware?

Try acpi_os_acquire_lock(acpi_gbl_hardware_lock).

But acpi_gbl_hardware_lock is defined in the ACPICA internal header
"drivers/acpi/acpica/acglobal.h",
you need to move it to public header, for example, include/acpi/acpixf.h

Lin Ming

>
> FWIW, the Windows drivers from Acer also access those IO ports directly
> (from userspace, no less, with a dumb kernel driver to provide port I/O
> to userspace and in the process introduce a huge security hole of
> course). There is no way of talking to this hardware via DSDT methods.
>
> --
> Hector Martin (hector@marcansoft.com)
> Public Key: http://www.marcansoft.com/marcan.asc