From a1d3154381e1bfdbca59bcdf9d4d719b0316fcda Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Mon, 11 Dec 2023 14:28:32 -0500
Subject: kernel/amd64: Update arch(9)

This commit cleans up arch(9) as a few things were
noticed. First, it would make sense to identify cores (described by
the cpu_info structure) in every arch ported, thus
the lapic_id has been changed to id so it can be shared. Some
annotations have also been added for the sake of clarity. The manpage
for arch(9) has also been cleaned up.

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 share/man/man9/arch.9        | 31 +++++++++++++++++++++++++++++--
 sys/arch/amd64/lapic.c       |  4 ++--
 sys/include/arch/amd64/cpu.h |  7 +++++--
 3 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/share/man/man9/arch.9 b/share/man/man9/arch.9
index 6948e81..94ccd6a 100644
--- a/share/man/man9/arch.9
+++ b/share/man/man9/arch.9
@@ -48,16 +48,43 @@ struct which contains CPU specific fields.
 
 Example
 .Ft cpu_info
-structure for x86_64 is shown below:
+structure shown below:
 
 .Bd -literal
 struct cpu_info {
+    /* Per-arch fields */
     void *pmap;                     /* Current pmap */
-    volatile uint32_t lapic_freq;
+    uint32_t id;
+    struct spinlock lock;
+    /* AMD64 */
     ...
 };
 .Ed
 
+There will be some per-architecture fields that, for the sake
+of keeping things tidy, should remain at the top of the struct.
+These fields will be described below.
+
+The
+.Ft pmap
+field points to the current virtual memory context
+which shall be NULL if not used.
+
+The
+.Ft id
+field simply identifies the CPU with a specific "ID".
+
+The
+.Ft lock
+field is a spinlock to prevent race conditions
+while accessing this structure. This must be acquired
+when accessing a
+.Ft cpu_info
+instance.
+
+There are also some common helper macros that shall
+be implemented, these are described below.
+
 The macro
 .Ft this_cpu()
 calls an internal function that fetches the
diff --git a/sys/arch/amd64/lapic.c b/sys/arch/amd64/lapic.c
index 1ea80c4..8058e3f 100644
--- a/sys/arch/amd64/lapic.c
+++ b/sys/arch/amd64/lapic.c
@@ -285,8 +285,8 @@ lapic_init(void)
     cur_cpu->lapic_tmr_freq = tmr_freq;
 
     /* Set the Local APIC ID */
-    cur_cpu->lapic_id = lapic_get_id();
+    cur_cpu->id = lapic_get_id();
 
-    BSP_KINFO("BSP Local APIC ID: %d\n", cur_cpu->lapic_id);
+    BSP_KINFO("BSP Local APIC ID: %d\n", cur_cpu->id);
     CPU_INFO_UNLOCK(cur_cpu);
 }
diff --git a/sys/include/arch/amd64/cpu.h b/sys/include/arch/amd64/cpu.h
index 59d1dcd..e93e8a2 100644
--- a/sys/include/arch/amd64/cpu.h
+++ b/sys/include/arch/amd64/cpu.h
@@ -46,10 +46,13 @@
  *      acquire the spinlock themselves!
  */
 struct cpu_info {
+    /* Per-arch fields  */
     void *pmap;                         /* Current pmap */
-    uint32_t lapic_id;
-    volatile size_t lapic_tmr_freq;
+    uint32_t id;
     struct spinlock lock;
+
+    /* AMD64 */
+    volatile size_t lapic_tmr_freq;
 };
 
 struct cpu_info *amd64_this_cpu(void);
-- 
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