[PATCH v9] ACPI / init: Invoke early ACPI initialization earlier

Dou Liyang douly.fnst at cn.fujitsu.com
Wed Sep 13 02:17:54 PDT 2017

Linux uses acpi_early_init() to put the ACPI table management into the
late stage from the early stage. This two stages are different. the
mapped ACPI tables in early stage is temporary and should be unmapped,
but in late stage, it is permanent and don't need to be unmapped.

Originally, mapping and parsing the DMAR table should be in the late stage.
However, Initializing interrupt delivery mode earlier will move it into
the early stage. This causes an ACPI error warning when Linux reallocates
the ACPI root tables.

Commit b064a8fa77df ("ACPI / init: Switch over platform to the ACPI mode
later") splits the ACPI early initialization code into acpi_early_init()
and acpi_subsystem_init(). This makes acpi_early_init() more independently

So, 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 at intel.com>
Signed-off-by: Dou Liyang <douly.fnst at cn.fujitsu.com>
Cc: linux-acpi at vger.kernel.org
Cc: Rafael J. Wysocki <rjw at rjwysocki.net>
Cc: Zheng, Lv <lv.zheng at intel.com>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: "H. Peter Anvin" <hpa at zytor.com>
Cc: x86 at kernel.org
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Will Deacon <will.deacon at arm.com>
Cc: linux-arm-kernel at lists.infradead.org
Cc: Tony Luck <tony.luck at intel.com>
Cc: Fenghua Yu <fenghua.yu at intel.com>
Cc: linux-ia64 at vger.kernel.org
Cc: yinghai at kernel.org
Cc: bhe at redhat.com
Cc: bp at alien8.de
 init/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/init/main.c b/init/main.c
index 0ee9c686..2fb98a4 100644
--- a/init/main.c
+++ b/init/main.c
@@ -664,12 +664,12 @@ asmlinkage __visible void __init start_kernel(void)
+	acpi_early_init();
 	if (late_time_init)
-	acpi_early_init();
 #ifdef CONFIG_X86
 	if (efi_enabled(EFI_RUNTIME_SERVICES))

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