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authorMichael S. Tsirkin <mst@redhat.com>2016-03-01 18:56:07 +0800
committerMichael S. Tsirkin <mst@redhat.com>2016-03-11 14:54:28 +0200
commitf20354910893310d5496ebb6edfc551d83d95343 (patch)
tree8a9bcec19faf0b9d864dee9f9b569d538fe90809 /hw/acpi/aml-build.c
parent3f3009c0983428f517b743c9de14858b1fdaacb7 (diff)
acpi: add build_append_named_dword, returning an offset in buffer
This is a very limited form of support for runtime patching - similar in functionality to what we can do with ACPI_EXTRACT macros in python, but implemented in C. This is to allow ACPI code direct access to data tables - which is exactly what DataTableRegion is there for, except no known windows release so far implements DataTableRegion. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'hw/acpi/aml-build.c')
-rw-r--r--hw/acpi/aml-build.c28
1 files changed, 28 insertions, 0 deletions
diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
index f26fa26802..ab89ca6380 100644
--- a/hw/acpi/aml-build.c
+++ b/hw/acpi/aml-build.c
@@ -258,6 +258,34 @@ static void build_append_int(GArray *table, uint64_t value)
}
}
+/*
+ * Build NAME(XXXX, 0x00000000) where 0x00000000 is encoded as a dword,
+ * and return the offset to 0x00000000 for runtime patching.
+ *
+ * Warning: runtime patching is best avoided. Only use this as
+ * a replacement for DataTableRegion (for guests that don't
+ * support it).
+ */
+int
+build_append_named_dword(GArray *array, const char *name_format, ...)
+{
+ int offset;
+ va_list ap;
+
+ build_append_byte(array, 0x08); /* NameOp */
+ va_start(ap, name_format);
+ build_append_namestringv(array, name_format, ap);
+ va_end(ap);
+
+ build_append_byte(array, 0x0C); /* DWordPrefix */
+
+ offset = array->len;
+ build_append_int_noprefix(array, 0x00000000, 4);
+ assert(array->len == offset + 4);
+
+ return offset;
+}
+
static GPtrArray *alloc_list;
static Aml *aml_alloc(void)