Add comment to elaborate on store-conditional result code (and remove

stale reference to machine.def).

arch/alpha/isa_desc:
    Add comment describing store-conditional result code
cpu/exec_context.hh:
    update comments

--HG--
extra : convert_revision : ac59e0ad7a9440cb6656617fdf05495b59c68f55

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/alpha/isa_desc b/arch/alpha/isa_desc
index e9b93a895..b5536525d 100644
--- a/arch/alpha/isa_desc
+++ b/arch/alpha/isa_desc
@@ -1808,11 +1808,19 @@ decode OPCODE default Unknown::unknown() {
 	0x2e: stl_c({{ EA = Rb + disp; }}, {{ Mem.ul = Ra<31:0>; }},
 		    {{
 			uint64_t tmp = Mem_write_result;
+			// see stq_c
 			Ra = (tmp == 0 || tmp == 1) ? tmp : Ra;
 		    }}, LOCKED);
 	0x2f: stq_c({{ EA = Rb + disp; }}, {{ Mem.uq = Ra; }},
 		    {{
 			uint64_t tmp = Mem_write_result;
+			// If the write operation returns 0 or 1, then
+			// this was a conventional store conditional,
+			// and the value indicates the success/failure
+			// of the operation.  If another value is
+			// returned, then this was a Turbolaser
+			// mailbox access, and we don't update the
+			// result register at all.
 			Ra = (tmp == 0 || tmp == 1) ? tmp : Ra;
 		    }}, LOCKED);
     }