From e3d8301932948c0ee8d27fb4caa4545d35bded6e Mon Sep 17 00:00:00 2001 From: Ved Shanbhogue Date: Thu, 27 Oct 2022 10:35:43 -0500 Subject: [PATCH 1/2] adding note recommended by AR --- zawrs.adoc | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/zawrs.adoc b/zawrs.adoc index 2502556..3f70e8c 100644 --- a/zawrs.adoc +++ b/zawrs.adoc @@ -55,4 +55,12 @@ The duration of a `WRS.STO` instruction's timeout may vary significantly within and among implementations. In typical implementations this duration should be roughly in the range of 10 to 100 times an on-chip cache miss latency or a cacheless access to main memory. + +`WRS.NTO`, unlike `WFI`, is not specified to cause an illegal instruction +exception if executed in U-mode when the governing `TW` bit is 0. `WFI` is +typically not expected to be used in U-mode and on many systems may immediately +or fairly quickly cause an illegal instruction exception if used at U-mode. +Unlike `WFI`, `WRS.NTO` is expected to be used by software in U-mode when +waiting on memory but without itself having a deadline for that wait to +complete. ==== From d1bb680043e02b160c961df3e70b48ec99993e1b Mon Sep 17 00:00:00 2001 From: Ved Shanbhogue Date: Thu, 27 Oct 2022 11:02:04 -0500 Subject: [PATCH 2/2] updating text --- zawrs.adoc | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/zawrs.adoc b/zawrs.adoc index 3f70e8c..3607342 100644 --- a/zawrs.adoc +++ b/zawrs.adoc @@ -58,9 +58,8 @@ cacheless access to main memory. `WRS.NTO`, unlike `WFI`, is not specified to cause an illegal instruction exception if executed in U-mode when the governing `TW` bit is 0. `WFI` is -typically not expected to be used in U-mode and on many systems may immediately -or fairly quickly cause an illegal instruction exception if used at U-mode. -Unlike `WFI`, `WRS.NTO` is expected to be used by software in U-mode when -waiting on memory but without itself having a deadline for that wait to -complete. +typically not expected to be used in U-mode and on many systems may promptly +cause an illegal instruction exception if used at U-mode. Unlike `WFI`, +`WRS.NTO` is expected to be used by software in U-mode when waiting on +memory but without itself having a deadline for that wait to complete. ====