Zhao Yakui wrote:
On Thu, 2008-11-27 at 17:42 +0800, Alexey Starikovskiy wrote:
Zhao Yakui wrote:
On Thu, 2008-11-27 at 04:03 +0800, Alexey Starikovskiy wrote:
This is hardly a "fix", you just disable EC on this machine... Famous
Yes. This can't fix the issue on the box of bug11884.
But in theory if the incorrect status is returned by
acpi_install_address_space_handler, the EC space handler should be
removed explicitly. Right? In such case the EC device will be disabled
on this box.
Wrong. If any function is allowed to fail, you should not call counter function
to recover -- you don't call free() on failed malloc(), you don't call close() on
failed open().
In the function of acpi_install_address_space_handler the following two
steps are done in ACPCA:
a. Install the space handler for one operation region. This space
handler is applied for the same type operation region of every device.
b. run the _REG object for all the operation regions using the space
id. It will enumerate the ACPI namespace to execute the _REG object for
the same operation region
Unregister space handler will do all these things in opposite order, thus calling
failed _REG object once again, causing more damage.
If the space handler is removed in the function of
acpi_install_address_space_handler when failure in _REG object happens,
it is unnecessary to remove the space handler explicitly.
But in fact maybe there exists the _REG object for other operation
region besides EC operation region. If failure in _REG object happens,
maybe the space handler should not be applied for the corresponding
device. PCI space handler is used by all the PCI devices. It is
unreasonable that all the PCI devices can't use the pci space handler if
OS fails in the _REG object of one PCI device.
So it is difficult to deal with this issue in the function of
acpi_install_address_space_handler.
Maybe it will be easy to deal with such issue in driver.
But if the EC space handler is not removed and EC flag in AML code
still indicates that EC operation region is already accessible, the EC
internal register will be accessed in AML code. At the same time the
memory region pointed by acpi_ec is already freed. This is the fourth
argument of ec_space_handler.
I already told you and here is second time -- your fixes come in wrong place.
You should fix acpi_install_address_space_handler(), not all the callers of it.
It is difficult for me to fix this issue in
acpi_install_address_space_handler. I am not willing to change the code
of ACPICA. It is not very reasonable that all the failures in _REG
object for all the operations region are ignored.
You have address space identifier in this function, so if you want your
workaround to be "only for EC", check it.
And it is also unreasonable that the space handler is removed for the
same type operation region of all the devices only because OS fails in
_REG object of one device.
If you have better method to fix such issue, please write it.
Yakui, why should I complete all your jobs?
Alex.
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