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-rw-r--r--include/acpi/actbl1.h12
1 files changed, 9 insertions, 3 deletions
diff --git a/include/acpi/actbl1.h b/include/acpi/actbl1.h
index 300d14e7c5d5..c41d6f96ed7d 100644
--- a/include/acpi/actbl1.h
+++ b/include/acpi/actbl1.h
@@ -79,9 +79,15 @@
#pragma pack(1)
/*
- * Note about bitfields: The u8 type is used for bitfields in ACPI tables.
- * This is the only type that is even remotely portable. Anything else is not
- * portable, so do not use any other bitfield types.
+ * Note: C bitfields are not used for this reason:
+ *
+ * "Bitfields are great and easy to read, but unfortunately the C language
+ * does not specify the layout of bitfields in memory, which means they are
+ * essentially useless for dealing with packed data in on-disk formats or
+ * binary wire protocols." (Or ACPI tables and buffers.) "If you ask me,
+ * this decision was a design error in C. Ritchie could have picked an order
+ * and stuck with it." Norman Ramsey.
+ * See http://stackoverflow.com/a/1053662/41661
*/
/*******************************************************************************