-----Original Message-----
From: Hans de Goede [mailto:hdegoede@xxxxxxxxxx]
Sent: Tuesday, February 28, 2017 6:32 AM
To: Zheng, Lv <lv.zheng@xxxxxxxxx>; Rafael J . Wysocki
<rjw@xxxxxxxxxxxxx>; Len Brown <lenb@xxxxxxxxxx>; Moore, Robert
<robert.moore@xxxxxxxxx>
Cc: linux-acpi@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx
Subject: Re: [PATCH] ACPICA: Detect duplicate SSDT tables
Hi,
On 28-02-17 06:19, Zheng, Lv wrote:
Hi,
From: Hans de Goede [mailto:hdegoede@xxxxxxxxxx]
Subject: [PATCH] ACPICA: Detect duplicate SSDT tables
Some machines have the exact (byte for byte) same SSDT tables
multiple times in the root_table_list.
Could you give a machine list here?
Currently I'm seeing this on a GPD win machine:
http://www.gpd.hk/gpdwin.asp
I thought I was seeing it on more machines, but those have different
apci table loading errors...
Detect this and silently skip the duplicates rather then printing a
scary looking set of errors.
Why will this matter to OSPMs?
Not sure what you mean with OSPMs but I can tell you why this matters in
general, Linux distributions like e.g. Fedora have been putting a lot of
work in a smooth boot experience where end users do not get any scary
text messages. For some more embedded like systems this even is a hard
requirement.
The kernel supports quiet kernel cmdline argument to silence normal
kernel messages, which is part of what is needed but messages with a log
level of error still get shown, breaking the "no scary text messages"
product requirement.
And should we add non-costless steps just in order to reduce errors,
Yes we should, work on that front has been happening for years, also the
CPU cost of this check is quite small, memcmp will only happen on
identically sized tables and even then it will exit as soon as a single
byte differs.
while the errors are on the contrary useful (in1dicating platform
issues)?
These errors are useful for developers / during testing but not in
production setups, esp. in the case of duplicate tables where not
loading the duplicate leads to 0 bad side effects.
I've an alternative proposal though, since this check just fixes a small
part of the early boot messages caused by SSDT loading and since the
code itself chooses to ignore any errors:
/* Ignore errors while loading tables, get as many as possible
*/
How about setting a global flag while loading these tables and making
ACPI_EXCEPTION calls log the exceptions with a log level of warning as
well as turning the final:
ACPI_ERROR((AE_INFO,
"%u table load failures, %u successful",
tables_failed, tables_loaded));
Into a warning ?
Regards,
Hans
Thanks
Lv
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/acpi/acpica/tbxfload.c | 41
++++++++++++++++++++++++++++++++++++++++-
1 file changed, 40 insertions(+), 1 deletion(-)
diff --git a/drivers/acpi/acpica/tbxfload.c
b/drivers/acpi/acpica/tbxfload.c index 82019c0..1971cd7 100644
--- a/drivers/acpi/acpica/tbxfload.c
+++ b/drivers/acpi/acpica/tbxfload.c
@@ -125,6 +125,44 @@ ACPI_EXPORT_SYMBOL_INIT(acpi_load_tables)
/***********************************************************************
********
*
+ * FUNCTION: acpi_tb_find_duplicate_ssdt
+ *
+ * PARAMETERS: table - validated acpi_table_desc of table
to check
+ * index - index of table to find a duplicate
of
+ *
+ * RETURN: TRUE if a duplicate is found, FALSE if not
+ *
+ * DESCRIPTION: Private helper function for acpi_tb_load_namespace
to
+ * avoid trying to load duplicate ssdt tables
+ *
+
+********************************************************************
+**********/ static u8 acpi_tb_find_duplicate_ssdt(struct
+acpi_table_desc *table, u32 index) {
+ struct acpi_table_desc *dup;
+ u32 i;
+
+ for (i = 0; i < index; ++i) {
+ dup = &acpi_gbl_root_table_list.tables[i];
+
+ if (!acpi_gbl_root_table_list.tables[i].address ||
+ (!ACPI_COMPARE_NAME(dup->signature.ascii, ACPI_SIG_SSDT)
+ && !ACPI_COMPARE_NAME(dup->signature.ascii,
+ ACPI_SIG_PSDT)
+ && !ACPI_COMPARE_NAME(dup->signature.ascii,
+ ACPI_SIG_OSDT))
+ || ACPI_FAILURE(acpi_tb_validate_table(dup))
+ || dup->length != table->length) {
+ continue;
+ }
+
+ if (memcmp(dup->pointer, table->pointer, table->length) == 0)
+ return TRUE;
+ }
+ return FALSE;
+}
+
+/*******************************************************************
+************
+ *
* FUNCTION: acpi_tb_load_namespace
*
* PARAMETERS: None
@@ -212,7 +250,8 @@ acpi_status acpi_tb_load_namespace(void)
ACPI_SIG_PSDT)
&& !ACPI_COMPARE_NAME(table->signature.ascii,
ACPI_SIG_OSDT))
- || ACPI_FAILURE(acpi_tb_validate_table(table))) {
+ || ACPI_FAILURE(acpi_tb_validate_table(table))
+ || acpi_tb_find_duplicate_ssdt(table, i)) {
continue;
}
--
2.9.3
