601 vs head.S
Franz.Sirl-kernel at lauterbach.com
Mon Feb 22 08:13:53 EST 1999
Am Sun, 21 Feb 1999 schrieb Paul Mackerras:
>Brad Midgley <brad at pht.com> wrote:
>> my quest is for a kernel that boots both on the 7200 and the imac. help me
>Found it... had to take out the 2 nop's in hash_page this time. Vger
>(cvs) and samba (rsync) have the fix, if you want a precompiled
>kernel, try ftp://ftp.linuxppc.org/linuxppc/kernel/powermac/test/vmlinux.
Ugh, a workaround again. As somebody will break that again for sure, I thought
a little bit about it and came up with the appended patch. An (possible?)
explanation is included. I tried it with 0-7 nop's at the old position after
the found_slot label and it always worked. I even did remove the SYNC here and
it still worked. For this final patch I left the SYNC in, cause I don't know
what it is good for. It is against Cort's 990216 vger snapshot, tested on my
--- head.S-org Wed Feb 17 06:59:32 1999
+++ head.S Sun Feb 21 22:20:49 1999
@@ -1361,13 +1361,6 @@
- * These nop's seem to be necessary to avoid getting a machine
- * check on the rfi on 601 processors.
#else /* __SMP__ */
* Between the tlbie above and updating the hash table entry below,
@@ -1441,7 +1434,22 @@
+ * These 8 nop's are here to avoid lockup of the 601 on the previous rfi
+ * instruction. They make sure that rfi gets a different cache sector than
+ * the following hash_page_out code and thus the rfi instruction is not
+ * prefetched by not-taken branch instructions in the hash_page code.
lis r2,hash_table_lock at ha
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