From 1a33f7b382a81283380c4e58af8a3e90bb9ff130 Mon Sep 17 00:00:00 2001
From: Charles Perkins <chuck@kuracali.com>
Date: Wed, 23 Dec 2020 16:59:48 -0800
Subject: [PATCH] send serial to stdio

---
 README.md |  6 +++++-
 shoe.asm  | 18 +++++++++---------
 toe.asm   | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+), 10 deletions(-)
 create mode 100644 toe.asm

diff --git a/README.md b/README.md
index 16a7d42..72015d0 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,7 @@ bare-bones nasm uefi application
 
 build with:
 * nasm -f bin shoe.asm -o shoe.efi
+* dd if=toe.bin of=shoe.efi bs=1 seek=20480 conv=notrunc
 * sudo mount disk.iso mnt
 * sudo cp shoe.efi mnt/EFI/BOOT/BOOTX64.EFI
 * sudo umount mnt
@@ -10,9 +11,12 @@ build with:
 get asm listing with:
 * objdump -Mintel -d shoe.efi
 
+show the bytes of the payload:
+* hexdump -ve '1/1 "%.2x "' toe.bin
+
 Launch QEMU with:
 
-* /usr/bin/qemu-system-x86_64 -machine accel=kvm -name guest=uefiguest -machine pc,accel=kvm,usb=off,dump-guest-core=off  -smp 2,sockets=2,cores=1,threads=1 -uuid 515645b7-ab3a-4e82-ba62-25751e4b523f -bios ./OVMF.fd -m 1G  -vga qxl -spice port=5900,addr=127.0.0.1,disable-ticketing -drive file=disk.iso 
+* /usr/bin/qemu-system-x86_64 -machine accel=kvm -name guest=uefiguest -machine pc,accel=kvm,usb=off,dump-guest-core=off  -smp 2,sockets=2,cores=1,threads=1 -uuid 515645b7-ab3a-4e82-ba62-25751e4b523f -bios ./OVMF.fd -m 1G  -vga qxl -spice port=5900,addr=127.0.0.1,disable-ticketing -drive file=disk.iso -serial stdio
 
 Launch the Spice viewer with:
 * remote-viewer spice://localhost:5900
diff --git a/shoe.asm b/shoe.asm
index b3cd445..83616e2 100644
--- a/shoe.asm
+++ b/shoe.asm
@@ -286,15 +286,15 @@ codesize equ $ - $$
 
 section .data follows=.text
 
-dmagic		dq 0x1122334455667788
-Handle          dq 0
-SystemTable     dq 0
-Interface       dq 0
-BS              dq 0
-RTS             dq 0
-STK             dq 0
-FB              dq 0
-FBS             dq 0
+dmagic		dq 0x1122334455667788 ;0
+Handle          dq 0     ;8
+SystemTable     dq 0     ;16
+Interface       dq 0     ;24
+BS              dq 0     ;32
+RTS             dq 0     ;40
+STK             dq 0     ;48
+FB              dq 0     ;56
+FBS             dq 0     ;64
 HR		dq 0
 VR		dq 0
 PPS		dq 0
diff --git a/toe.asm b/toe.asm
new file mode 100644
index 0000000..4a6cb8e
--- /dev/null
+++ b/toe.asm
@@ -0,0 +1,32 @@
+bits 64
+org 0x8005000
+section .text
+global _start
+_start:
+
+FB    equ 0x8003000 + 56
+FBS   equ 0x8003000 + 64
+
+jmp begin
+
+dw	0
+dd	1
+dd	2
+dd	3
+dd	4
+dd	5
+dd	6
+dd	7
+
+begin:
+mov r8, 0x1111BBBB66660000
+mov rcx, [FB]
+mov rax, [FBS]
+Q:
+sub rax, 8
+mov [rcx+rax],r8
+jnz Q
+
+jmp $
+
+