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+gorka writes:
+---
+I have userspace on the gumstix [xscale, not omap].  The problem that
+got me in trouble was that in lexception.s (or l.s),
+
+	MOVM.DB.W [R0-R14], (R13)
+
+works differently for this architecture (and probably for others, as
+it is unclear how it should behave by reading the arm specs).  This
+happens only for kernel faults as the others (syscall, user faults)
+use MOVM.DB.W.S which uses the banked user registers.
+
+The problem is that in this arch the value of R13 saved is the value
+after R13 itself has been modified, whereas in the others (bitsy,
+pico...), it was the value before.  Adding 4*15 to the stack before
+the RFE solves the problem.
+---
+
+In fact, the 2005 ARM arch. ref. man. (ARM DDI 0100I) says, under STM (1),
+that if Rn appears in the set of registers (and isn't the first one)
+and .W is specified, the stored value of Rn is unpredictable.
+The arm v7-ar arch. ref. man. says such usage is obsolete.