From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Thu, 1 Nov 2018 22:29:17 +0000 (+0000)
Subject: record multi-lr/sc discussion
X-Git-Tag: convert-csv-opcode-to-binary~4874
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=4873f6c09cbbe46bab5e3bd070b19de7f5de9944;p=libreriscv.git

record multi-lr/sc discussion
---

diff --git a/simple_v_extension.mdwn b/simple_v_extension.mdwn
index 3a16606a1..a62cbca77 100644
--- a/simple_v_extension.mdwn
+++ b/simple_v_extension.mdwn
@@ -1657,6 +1657,29 @@ in advance to avoid.
 
 TBD: floating-point compare and other exception handling
 
+------
+
+Multi-LR/SC
+
+Please don't try to use the L1 itself.
+
+Use the Load and Store buffers which capture instruction state prior
+to being accessed in the L1 (and prior to data arriving in the case of
+Store buffer).
+
+Also, use the L1 Miss buffers as these already HAVE to be snooped by
+coherence traffic. These are used to monitor that all participating
+cache lines remain interference free, and amalgamate same into a CPU
+signal accessible ia branch or predicate.
+
+The Load buffers manage inbound traffic
+The Store buffers manage outbound traffic.
+
+Done properly, the participating cache lines can exceed the associativity
+of the L1 cache without architectural harm (may incur additional latency).
+
+<https://groups.google.com/d/msg/comp.arch/QVl3c9vVDj0/ol_232-pAQAJ>
+
 # References
 
 * SIMD considered harmful <https://www.sigarch.org/simd-instructions-considered-harmful/>