From 39c64a75878480ca96b2ed61d89c51c199ade21a Mon Sep 17 00:00:00 2001
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Mon, 9 Dec 2024 22:23:10 +0100
Subject: Comment on the reason for the different CPU_NUMBER versions

---
 i386/i386/cpu_number.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/i386/i386/cpu_number.h b/i386/i386/cpu_number.h
index 67c19e9b..547e0498 100644
--- a/i386/i386/cpu_number.h
+++ b/i386/i386/cpu_number.h
@@ -41,12 +41,14 @@
 #define	CX(addr, reg)	addr(,reg,8)
 #endif
 
+/* Slow version, always works */
 #define	CPU_NUMBER_NO_STACK(reg)	\
 	movl	%cs:lapic, reg		;\
 	movl	%cs:APIC_ID(reg), reg	;\
 	shrl	$24, reg		;\
 	movl	%cs:CX(cpu_id_lut, reg), reg	;\
 
+/* Fast version, requires a stack */
 #ifdef __i386__
 /* Never call CPU_NUMBER_NO_GS(%esi) */
 #define CPU_NUMBER_NO_GS(reg)		\
@@ -86,6 +88,7 @@
 	popq	%rsi
 #endif
 
+/* Fastest version, requires gs being set up */
 #define CPU_NUMBER(reg)	\
 	movl    MY(CPU_ID), reg;
 
-- 
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