From 33b8fcecfbff405a22f950e4dfd83d6e57500e23 Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jackpot51@gmail.com>
Date: Fri, 26 Aug 2022 08:08:24 -0600
Subject: [PATCH] Sync x86_64 trampoline with bootloader
---
src/asm/x86_64/trampoline.asm | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/src/asm/x86_64/trampoline.asm b/src/asm/x86_64/trampoline.asm
index 0fff14fa..538ff1b7 100644
--- a/src/asm/x86_64/trampoline.asm
+++ b/src/asm/x86_64/trampoline.asm
@@ -26,24 +26,22 @@ startup_ap:
; initialize stack to invalid value
mov sp, 0
- ;cr3 holds pointer to PML4
+ ; cr3 holds pointer to PML4
mov edi, [trampoline.page_table]
mov cr3, edi
- ; Enable FPU
+ ; enable FPU
mov eax, cr0
and al, 11110011b ; Clear task switched (3) and emulation (2)
or al, 00100010b ; Set numeric error (5) monitor co-processor (1)
mov cr0, eax
- ; 18: Enable OSXSAVE
- ; 10: Unmasked SSE exceptions
; 9: FXSAVE/FXRSTOR
; 7: Page Global
; 5: Page Address Extension
; 4: Page Size Extension
mov eax, cr4
- or eax, 1 << 18 | 1 << 10 | 1 << 9 | 1 << 7 | 1 << 5 | 1 << 4
+ or eax, 1 << 9 | 1 << 7 | 1 << 5 | 1 << 4
mov cr4, eax
; initialize floating point registers
@@ -52,12 +50,13 @@ startup_ap:
; load protected mode GDT
lgdt [gdtr]
+ ; enable long mode
mov ecx, 0xC0000080 ; Read from the EFER MSR.
rdmsr
or eax, 1 << 11 | 1 << 8 ; Set the Long-Mode-Enable and NXE bit.
wrmsr
- ;enabling paging and protection simultaneously
+ ; enabling paging and protection simultaneously
mov ebx, cr0
; 31: Paging
; 16: write protect kernel
--
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