[PATCH] Avoid loading of ACPI tables twice

[Thomas Renninger <trenn-l3A5Bk7waGM@public.gmane.org>]

Hi,

CC'ing Venkatesh as the syslog output and symptoms look
similar to a speedstep-centrino bug (invoking _PDC twice).

I have a machine with following DSDT code:

Processor (CPU1, 0x01, 0x00000810, 0x06)
        {
            OperationRegion (SSDT, SystemMemory, 0x1DFD4050, 0x03CC)
            ...
            Method (_PDC, 1, NotSerialized)
            {
                ...
                Load (SSDT, HNDL)
                ...
            }
        }

The machine works fine using acpi-cpufreq.

If loading the speedstep-centrino module is tried, the _PDC function is invoked
and the SSDT is loaded a second time which results in:

linux kernel: ACPI: CPU0 (power states: C1[C1] C2[C2])
linux kernel: ACPI: Processor [CPU1] (supports 8 throttling states)
linux kernel:  dswload-0294: *** Error: Looking up [ACST] in namespace, AE_ALREADY_EXISTS
linux kernel:  psparse-0601 [20] ps_parse_loop         : During name lookup/catalog, AE_ALREADY_EXISTS
linux kernel:  psparse-1140: *** Error: Method execution failed [\_PR_.CPU1._PDC] (Node ddfcd3a8), AE_ALREADY_EXISTS

and a kernel freeze with different backtraces later:
linux kernel: Unable to handle kernel paging request at virtual address XYZ

This patch worksarounds/fixes this problem on this machine.
Could someone have a look at it, please.

The OEM id of new tables is compared with already loaded once. Loading is
denied if the table already exists in the kernel's AML namespace.

--- drivers/acpi/namespace/nsload.c.orig        2005-06-03 05:40:58.000000000 -0600
+++ drivers/acpi/namespace/nsload.c     2005-06-06 07:51:24.000000000 -0600
@@ -45,7 +45,7 @@
 #include <acpi/acpi.h>
 #include <acpi/acnamesp.h>
 #include <acpi/acdispat.h>
-
+#include <acpi/actables.h>

 #define _COMPONENT          ACPI_NAMESPACE
         ACPI_MODULE_NAME    ("nsload")
@@ -72,7 +72,8 @@
        struct acpi_namespace_node      *node)
 {
        acpi_status                     status;
-
+       struct acpi_table_desc          *table_desc_loaded;
+       int                             count;

        ACPI_FUNCTION_TRACE ("ns_load_table");

@@ -104,6 +105,19 @@
        }

        /*
+        * Check whether the table already exists - if yes, deny loading it again
+
+       for (count = 0;count < acpi_gbl_table_lists[table_desc->type].count; count++){
+               table_desc_loaded = acpi_gbl_table_lists[table_desc->type].next;
+               if (table_desc_loaded->loaded_into_namespace &&
+                   !memcmp(table_desc_loaded->pointer->oem_table_id, table_desc->pointer->oem_table_id, 8)){
+                       ACPI_REPORT_WARNING (("Table %s has already been loaded (not bad)\n",
+                                             table_desc->pointer->oem_table_id));
+                       return (AE_ALREADY_EXISTS);
+               }
+       }
+
+       /*
         * Parse the table and load the namespace with all named
         * objects found within.  Control methods are NOT parsed
         * at this time.  In fact, the control methods cannot be






     Thomas



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