[parisc-linux-cvs] Hack for palo with >= 2G RAM

[bame@riverrock.org]

When palo's stack and heap got moved up to the top of the first memory
module, things went wrong for machines with >= 2G ram.  The culprit
appears to be
sign extension into the upper half of the double-word registers.  Perhaps
palo could be changed to prevent this sign extension, but for now it's
easier to limit the "top" of RAM to 1G.  This still allows for a
more than generous ram disk while also using small-ram boxes efficiently.

Index: crt0.S
===================================================================
RCS file: /home/cvs/parisc/palo/ipl/crt0.S,v
retrieving revision 1.10
retrieving revision 1.11
diff -u -r1.10 -r1.11
--- crt0.S	2001/02/09 04:06:22	1.10
+++ crt0.S	2001/02/14 21:31:44	1.11
@@ -45,6 +45,16 @@
 	ldo	R%(IMM_MAX_MEM)(%r3), %r3
 	ldw	0(%r3), %r3
 
+	/* due to sign extension problems and PDC, limit RAM to 1G */
+	/* this isn't efficient assembly but it doesn't matter here either */
+#define ARTIFICIAL_LIMIT (1*1024*1024*1024)
+	ldil	L%(ARTIFICIAL_LIMIT), %r4
+	ldo	R%(ARTIFICIAL_LIMIT)(%r4), %r4
+	cmpb,<<	%r3, %r4, limit_ok
+	nop
+	copy	%r4, %r3
+
+limit_ok:
 	/* stack is at top of initial mem module */
 #define STACK_SIZE (64 * 1024)
 	ldil	L%(STACK_SIZE), %r4