aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorOliver O'Halloran <oohall@gmail.com>2016-08-11 14:10:19 +1000
committerStewart Smith <stewart@linux.vnet.ibm.com>2016-08-11 16:31:33 +1000
commitc6a6391892539450a84d3dd69f4d83ea1a1b04d6 (patch)
tree551ba7f9bd491b6e112d3c0ae1ba1af0c613b283
parentf102c9d19078aba5b86394708d6c98a6795cb84a (diff)
downloadskiboot-c6a6391892539450a84d3dd69f4d83ea1a1b04d6.zip
skiboot-c6a6391892539450a84d3dd69f4d83ea1a1b04d6.tar.gz
skiboot-c6a6391892539450a84d3dd69f4d83ea1a1b04d6.tar.bz2
head.S: document opal_naca
On P7 machines OPAL can be loaded as a replacement for PHYP or in an OPAL specific mode. In OPAL mode 0x0 contains a pointer to the OPAL specific variant of the NACA which defines the entrypoint to OPAL, etc. Later machines use the same load method for for PHYP and OPAL and do not need the OPAL specific NACA, but this needs to be kept around for backwards compatibility. Signed-off-by: Oliver O'Halloran <oohall@gmail.com> Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
-rw-r--r--asm/head.S7
1 files changed, 4 insertions, 3 deletions
diff --git a/asm/head.S b/asm/head.S
index 227b1c3..8cb2069 100644
--- a/asm/head.S
+++ b/asm/head.S
@@ -44,8 +44,9 @@
. = 0
.global __head
__head:
- /* When booted as an OPAL LID, this is a pointer to the OPAL
- * variant of the NACA
+ /*
+ * When booting a P7 machine in OPAL mode this pointer is used to
+ * find the opal variant of the NACA. Unused on other machines.
*/
.llong opal_naca
@@ -783,7 +784,7 @@ hv_lid_load_table:
/*
*
- * OPAL variant of NACA
+ * OPAL variant of NACA. This is only used when booting a P7 in OPAL mode.
*
*/
.global opal_naca