Difference between revisions of "ACPI"

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   * make sure that you reserve _RAMBASE - LB_MEM_TOPK
   * SMP might need some fixes
+=== ACPI bytecode generator ===
+Some ACPI stuff is generated runtime. To achieve this goal we have a AML code generator which generates binary
+ACPI bytecode. Such code then resides typically in SSDT table. There is a helper function which creates such
+table - acpi_create_ssdt_generator(). The content of the table is created through callback function acpi_fill_ssdt_generator(). So far we have two big users of the generator k8acpi_write_vars() and amd_model_fxx_generate_powernow(). The first function will generate some runtime configuration of HT bus and PCI decode ranges. Second function generates the P-States.
+The available functions are in acpigen.h. Mostly there are functions generating some primitive named data structures. However sometime is necessary to put more data to a package. ACPI AML code needs to know the block
+lengths. The len is unknown until we have filled the payload of such package. Therefore when we are done, we need
+to call function acpigen_patch_len(int len) which will patch last object (package) which need patching. It uses
+stack internally so more structures can be nested. Look to acpigen.c and learn what functions call  acpigen_write_len_f() - those needs patching.
 === Debugging ACPI ===

Revision as of 20:37, 12 April 2009