[PATCH V2 1/3] acpi: madt: Use 20 as the GIC ITS node length

[Jeffrey Hugo]

The ACPI 6.0 spec technically defines the GIC ITS node length as 16,
however the conbination of all defined fields is 20 bytes, so the length is
really 20.  The spec defined length is corrected in following revisions of
the spec.

20 is what ACPI implementations are expected to be using in practice, so
updating the test to use 20 despite the spec definition has the test match
the real world, updates the test implementation to match the test
documentation, and allows the test to correctly find the start of any nodes
following a GIC ITS node in the MADT table.

Signed-off-by: Jeffrey Hugo <jhugo at codeaurora.org>
---
 src/acpi/madt/madt.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/acpi/madt/madt.c b/src/acpi/madt/madt.c
index e260222..141405d 100644
--- a/src/acpi/madt/madt.c
+++ b/src/acpi/madt/madt.c
@@ -183,7 +183,15 @@ static struct acpi_madt_subtable_lengths spec_info[] = {
 		.madt_version = 3,
 		.num_types = 16,
 		.lengths = { 8, 12, 10, 8, 6, 12, 16, SUBTABLE_VARIABLE,
-			     16, 16, 12, 80, 24, 24, 16, 16 }
+			     16, 16, 12, 80, 24, 24, 16, 20 }
+		/*
+		 * The spec technically defines the GIC ITS node length to be
+		 * 16, but this is a clear mistake as the fields add up to be
+		 * length 20, and the length was corrected in the next revision.
+		 * Test for 20, as that is what is expected to be used in real,
+		 * implementations and using length 20 ensures that the test can
+		 * correctly find the start of any following nodes.
+		 */
 	},
 	{ /* terminator */
 		.major_version = 0,
-- 
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