Re: [PATCH] ACPICA / Interpreter: Fix a regression triggered because of wrong Linux ECDT support

From: Rafael J. Wysocki
Date: Thu Mar 10 2016 - 17:09:14 EST

On Thursday, March 10, 2016 10:54:29 AM Lv Zheng wrote:
> It is reported that the following commit triggers regressions:
> Linux commit: efaed9be998b5ae0afb7458e057e5f4402b43fa0
> ACPICA commit: 31178590dde82368fdb0f6b0e466b6c0add96c57
> Subject: ACPICA: Events: Enhance acpi_ev_execute_reg_method() to
> ensure no _REG evaluations can happen during OS early boot
> stages
> This is because that the ECDT support is not corrected in Linux, and Linux
> requires to execute _REG for ECDT (though this sounds so wrong), we need to
> ensure acpi_gbl_namespace_initialized is set before ECDT probing in order
> for _REG to be executed. Since we have to move
> "acpi_gbl_namespace_initialized = TRUE" to the initialization step
> happening before ECDT probing, acpi_load_tables() is the best candidate for
> now. Thus this patch fixes the regression by doing so.
> But if the ECDT support is fixed, Linux will not execute _REG for ECDT, and
> ECDT probing will happen before acpi_load_tables(). At that time, we still
> want to ensure acpi_gbl_namespace_initialized is set after executing
> acpi_ns_initialize_objects() (under the condition of
> acpi_gbl_group_module_level_code = FALSE), this patch also moves
> acpi_ns_initialize_objects() to acpi_load_tables() accordingly.
> Since acpi_ns_initialize_objects() doesn't seem to be skippable, this
> patch also removes ACPI_NO_OBJECT_INIT for the one invoked in
> acpi_load_tables(). And since the default region handlers should always be
> installed before loading the tables, this patch also removes useless
> acpi_gbl_group_module_level_code check accordingly. Reported by Chris
> Bainbridge, Fixed by Lv Zheng.
> Reported-and-tested-by: Chris Bainbridge <chris.bainbridge@xxxxxxxxx>
> Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>

This is a bit too late for v4.5, so I'm queuing it up for 4.6 on top of
the other ACPICA changes already in my tree.

It actually may go to 4.5-stable I think, but first I'd like it to spend
some time in the mainline in case there are side-effects.