Hi,
At 07/14/2017 01:52 PM, Dou Liyang wrote:
Linux uses acpi_early_init() to put the ACPI table management into
the late stage from the early stage where the mapped ACPI tables is
temporary and should be unmapped.
But, now initializing interrupt delivery mode should map and parse the
DMAR table earlier in the early stage. This causes an ACPI error when
Linux reallocates the ACPI root tables. Because Linux doesn't unmapped
the DMAR table after using in the early stage.
Invoke acpi_early_init() earlier before late_time_init(), Keep the DMAR
be mapped and parsed in late stage like before.
Reported-by: Xiaolong Ye <xiaolong.ye@xxxxxxxxx>
Signed-off-by: Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>
Cc: linux-acpi@xxxxxxxxxxxxxxx
Cc: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
Cc: Zheng, Lv <lv.zheng@xxxxxxxxx>
Cc: Julian Wollrath <jwollrath@xxxxxx>
---
Test in my own PC(Lenovo M4340).
Ask help for doing regression testing for the bug said in commit c4e1acbb35e4
("ACPI / init: Invoke early ACPI initialization later").
Now, I can prove this patch doesn't result in the bug[1] which made the
fast TSC calibration using PIT failed in a Thinkpad x121e (AMD E-450
APU).
The true reason of the bug is enabling ACPI subsystem earlier than
using PIT, not the SCI setup. invoking acpi_enable_subsystem() later
could fix this bug as Julian tested and said[2].
And, I found that Commit b064a8fa77df (" ACPI / init: Switch over
platform to the ACPI mode later") split the ACPI early initialization
code into acpi_early_init() and acpi_subsystem_init(). executing
acpi_enable_subsystem() at the original early ACPI initialization spot.
The sequence of them shows below:
start_kernel
+---------------+
|
+--> .......
|
| late_time_init()
+--> +-------+
|
+--> .......
|
| acpi_early_init()
+--> +-------+
|
+--> .......
|
| acpi_subsystem_init()
+-> +--------+
We make sure the acpi_subsystem_init() is called later than
late_time_init(), the bug will be avoided.
This patch changes the sequence of late_time_init() and
acpi_early_init(), doesn't effect acpi_subsystem_init().
So, this patch is OK.
Btw, Thanks very much for Borislav Petkov, he will have access to
Thinkpad x121e from Mid-August and will test this series.
[1] https://lkml.org/lkml/2014/3/10/123
[2] https://lkml.org/lkml/2014/3/12/311
Thanks
dou.
init/main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/init/main.c b/init/main.c
index df58a41..7a09467 100644
--- a/init/main.c
+++ b/init/main.c
@@ -654,12 +654,12 @@ asmlinkage __visible void __init start_kernel(void)
kmemleak_init();
setup_per_cpu_pageset();
numa_policy_init();
+ acpi_early_init();
if (late_time_init)
late_time_init();
calibrate_delay();
pidmap_init();
anon_vma_init();
- acpi_early_init();
#ifdef CONFIG_X86
if (efi_enabled(EFI_RUNTIME_SERVICES))
efi_enter_virtual_mode();
--
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