OEM tables can be installed via RSDT/XSDT, in this case, they have already
been created under /sys/firmware/acpi/tables.
For this kind of tables, normally LoadTable opcode will be executed to load
them. If LoadTable opcode is executed after acpi_sysfs_init(),
acpi_sysfs_table_handler() will be invoked, thus a redundant table file
will be created under /sys/firmware/acpi/tables/dynamic. Then running
"acpidump" on such platform results in an error, complaining blank empty
table (see Link 1 below).
The bug can be reproduced by customizing an OEM1 table, allowing it to be
overridden via 'table_sigs' (drivers/acpi/tables.c), adding the following
code to the customized DSDT to load it:
Name (OEMH, Zero)
Name (OEMF, One)
If (LEqual (OEMF, One)) {
Store (LoadTable ("OEM1", "Intel", "Test"), OEMH)
Store (Zero, OEMF)
}
In order to make sure that the OEM1 table is installed after
acpi_sysfs_init(), acpi_sysfs_init() can be moved before invoking
acpi_load_tables(). Then the following command execution result can be
seen:
# acpidump > acpidump.txt
Could not read table header: /sysfs/firmware/acpi/tables/dynamic/OEM12
Could not get ACPI table at index 17, AE_BAD_HEADER
Link: https://bugzilla.kernel.org/show_bug.cgi?id=150841 # [1]
Link: https://github.com/acpica/acpica/commit/ed6a5fbc
Reported-by: Jason Voelz <jason.voelz@xxxxxxxxx>
Reported-by: Francisco Leoner <francisco.j.lenoer.soto@xxxxxxxxx>
Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
---
drivers/acpi/sysfs.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
index 703c993..c88d4bd 100644
--- a/drivers/acpi/sysfs.c
+++ b/drivers/acpi/sysfs.c
@@ -383,7 +383,7 @@ acpi_status acpi_sysfs_table_handler(u32 event, void *table, void *context)
struct acpi_table_attr *table_attr;
switch (event) {
- case ACPI_TABLE_EVENT_LOAD:
+ case ACPI_TABLE_EVENT_INSTALL:
table_attr =
kzalloc(sizeof(struct acpi_table_attr), GFP_KERNEL);
if (!table_attr)
@@ -397,7 +397,9 @@ acpi_status acpi_sysfs_table_handler(u32 event, void *table, void *context)
} else
list_add_tail(&table_attr->node, &acpi_table_attr_list);
break;
+ case ACPI_TABLE_EVENT_LOAD:
case ACPI_TABLE_EVENT_UNLOAD:
+ case ACPI_TABLE_EVENT_UNINSTALL:
/*
* we do not need to do anything right now
* because the table is not deleted from the
--
1.7.10
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