[src/trunk]: src/sys/arch/aarch64/aarch64 Improve comments

[skrll <skrll%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/db0b849f2c3e
branches:  trunk
changeset: 937349:db0b849f2c3e
user:      skrll <skrll%NetBSD.org@localhost>
date:      Sun Aug 16 10:08:42 2020 +0000

description:
Improve comments

diffstat:

 sys/arch/aarch64/aarch64/locore.S |  15 ++++++++++-----
 1 files changed, 10 insertions(+), 5 deletions(-)

diffs (49 lines):

diff -r f378174f87b9 -r db0b849f2c3e sys/arch/aarch64/aarch64/locore.S
--- a/sys/arch/aarch64/aarch64/locore.S Sun Aug 16 09:41:50 2020 +0000
+++ b/sys/arch/aarch64/aarch64/locore.S Sun Aug 16 10:08:42 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: locore.S,v 1.70 2020/08/12 13:19:35 skrll Exp $        */
+/*     $NetBSD: locore.S,v 1.71 2020/08/16 10:08:42 skrll Exp $        */
 
 /*
  * Copyright (c) 2017 Ryo Shimizu <ryo%nerv.org@localhost>
@@ -38,7 +38,7 @@
 #include <aarch64/hypervisor.h>
 #include "assym.h"
 
-RCSID("$NetBSD: locore.S,v 1.70 2020/08/12 13:19:35 skrll Exp $")
+RCSID("$NetBSD: locore.S,v 1.71 2020/08/16 10:08:42 skrll Exp $")
 
 #ifdef AARCH64_DEVICE_MEM_STRONGLY_ORDERED
 #define        MAIR_DEVICE_MEM         MAIR_DEVICE_nGnRnE
@@ -454,13 +454,15 @@
        msr     tpidr_el0, xzr
        msr     tpidrro_el0, xzr
 
-       /* set curcpu(), and fill curcpu()->ci_{midr,mpidr} */
        mov     x0, #CPU_INFO_SIZE
        mul     x0, x27, x0
        adrl    x1, _C_LABEL(cpu_info_store)
        add     x0, x0, x1              /* x0 = &cpu_info_store[cpuindex] */
+
+       /* temporarily set tpidr_el1 to curcpu until the idle lwp is setup */
        msr     tpidr_el1, x0           /* tpidr_el1 = curcpu = x0 */
 
+       /* fill curcpu()->ci_{midr,mpidr} */
        mrs     x1, midr_el1
        str     x1, [x0, #CI_MIDR]      /* curcpu()->ci_cpuid = midr_el1 */
        mrs     x1, mpidr_el1
@@ -508,8 +510,11 @@
        b       1b
 9:
 
-       /* fill my cpu_info */
-       mrs     x0, tpidr_el1           /* curcpu */
+       /*
+        * set curlwp (tpidr_el1 and curcpu()->ci_curlwp) now we know the
+        * idle lwp from curcpu()->ci_idlelwp
+        */
+       mrs     x0, tpidr_el1           /* curcpu (temporarily) */
        ldr     x1, [x0, #CI_IDLELWP]   /* x0 = curcpu()->ci_idlelwp */
        msr     tpidr_el1, x1           /* tpidr_el1 = curlwp = x1 */
        str     x1, [x0, #CI_CURLWP]    /* curlwp is idlelwp */