【openwrt】使用qemu模拟mt7628 并成功运行uboot、OpenWrt、NetBSD
本帖最后由 sunsili 于 2024-1-30 15:54 编辑【openwrt】使用qemu模拟mt7628 并成功运行uboot、OpenWrt、NetBSD
前言：
代码实现不一定正确, 因为MTK不公开SOC内部的实现细节,这个模拟器的实现依据是我的对此芯片的了解程度以及Linux/Uboot/NetBSD里面的驱动代码.
项目地址: https://github.com/newluhux/qemu-mt7628
下载QEMU 应用PATCH 然后构建
git clone https://gitlab.com/qemu-project/qemu
git clone https://github.com/newluhux/qemu-mt7628
cd ./qemu/
git branch mt7628
git switch mt7628
for i in ../qemu-mt7628/000*.patch
do
git am < $i
done
./configure --cc=gcc --cxx=g++ --target-list=mipsel-softmmu
make -j$(nproc)
make check
启动主线uboot
wget http://musl.cc/mipsel-linux-muslsf-cross.tgz
tar xf mipsel-linux-muslsf-cross.tgz
cd mipsel-linux-muslsf-cross/bin/
export PATH=$PATH:$(pwd)
cd -
git clone https://github.com/u-boot/u-boot
cd u-boot
cp ./configs/linkit-smart-7688_defconfig ./.config
make ARCH=mips CROSS_COMPILE=mipsel-linux-musl- menuconfig
# you need select:
# CONFIG_REMAKE_ELF=y
make ARCH=mips CROSS_COMPILE=mipsel-linux-musl- -j$(nproc)
# create a blank flash image
dd if=/dev/zero of=flash_16M.bin count=16 bs=1M
../qemu/qemu-system-mipsel -M mt7628 \
-serial telnet:localhost:4000,server \
-serial telnet:localhost:4001,server \
-serial telnet:localhost:4002,server \
-drive if=mtd,file=flash_16M.bin,type=raw \
-usb \
-kernel ./u-boot.elf
使用telnet连接串口:
$ telnet localhost 4002
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
U-Boot 2022.04 (Feb 14 2023 - 15:32:34 +0000)
CPU: MediaTek MT7628A ver:1 eco:2
Boot:DDR2, SPI-NOR 3-Byte Addr, CPU clock from XTAL
Clock: CPU: 575MHz, Bus: 191MHz, XTAL: 25MHz
Model: LinkIt-Smart-7688
DRAM:256 MiB
Core:54 devices, 15 uclasses, devicetree: separate
Loading Environment from SPIFlash... SF: Detected w25q128 with page
size 256 Bytes, erase size 4 KiB, total 16 MiB
Net:
Warning: eth@10110000 (eth0) using random MAC address - 96:0d:9e:0d:3f:ea
eth0: eth@10110000
=>
现在你可以使用tftp或者fatload命令来加载固件到内存,然后使用sf写入到 spi flash
最后使用bootm来启动固件
启动OpenWRT固件
在此之前你需要构建一个主线的uboot用于启动uImage，然后执行:
cp /path/to/uboot/uboot.elf ./uboot.elf
wget https://downloads.openwrt.org/re ... shfs-sysupgrade.bin
dd if=/path/to/uboot/uboot-with-spl.bin of=flash.bin
dd if=/dev/zero bs=1M count=1 >> flash.bin
truncate -s 327680 flash.bin
dd if=./openwrt-22.03.3-ramips-mt76x8-vocore_vocore2-squashfs-sysupgrade.bin
>> flash.bin
dd if=/dev/zero bs=1M count=16 >> flash.bin
truncate -s 16M flash.bin
/path/to/qemu-build/qemu-system-mipsel -M mt7628 \
-serial telnet:localhost:4000,server,nowait \
-serial telnet:localhost:4001,server,nowait \
-serial telnet:localhost:4002,server \
-kernel ./uboot.elf \
-drive if=mtd,file=flash_16M.bin,type=raw \
-usb
使用telnet 连接串口
$ telnet localhost 4002
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
U-Boot 2022.04 (Feb 14 2023 - 15:32:34 +0000)
CPU: MediaTek MT7628A ver:1 eco:2
Boot:DDR2, SPI-NOR 3-Byte Addr, CPU clock from XTAL
Clock: CPU: 575MHz, Bus: 191MHz, XTAL: 25MHz
Model: LinkIt-Smart-7688
DRAM:256 MiB
Core:54 devices, 15 uclasses, devicetree: separate
Loading Environment from SPIFlash... SF: Detected w25q128 with page
size 256 Bytes, erase size 4 KiB, total 16 MiB
Net:
Warning: eth@10110000 (eth0) using random MAC address - 96:0d:9e:0d:3f:ea
eth0: eth@10110000
使用 `bootm 0x1c050000` 来启动 openwrt
启动主线NetBSD
ref: https://www.netbsd.org/docs/guide/en/chap-build.html
NetBSD在8.0以及之后的版本加入了mt7628支持，你可以使用Linux/NetBSD/Other UNIX 来交叉编译 NetBSD，构建NetBSD内核是十分容易的(在我的Slackware Linux 机器上):
mkdir ./netbsd/
cd ./netbsd/
wget https://ftp.NetBSD.org/pub/NetBS ... ar_files/src.tar.gz
tar -zxf src.tar.gz
cd ./src/
./build.sh -U -O ~/obj -j$(nproc) -m evbmips -a mipsel tools
cd sys/arch/evbmips/conf/
~/obj/tooldir.HOST/bin/nbconfig LINKITSMART7688
cd ../compile/LINKITSMART7688/
~/obj/tooldir.HOST/bin/nbmake-evbmips depend
~/obj/tooldir.HOST/bin/nbmake-evbmips
构建成功后你会获得一个 './netbsd' 的文件
file ./netbsd
netbsd: ELF 32-bit LSB executable, MIPS, MIPS32 rel2 version 1 (SYSV),
statically linked, for NetBSD 9.3, with debug_info, not stripped
运行它：
/path/to/qemu-build/qemu-system-mipsel -M mt7628 \
-serial telnet:localhost:4000,server,nowait \
-serial telnet:localhost:4001,server,nowait \
-serial telnet:localhost:4002,server \
-kernel ./netbsd
连接串口,你可以看到netbsd内核的启动日志:
telnet localhost 4002
Trying ::1...
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
[ 1.0000000] MIPS32/64 params: cpu arch: 128
[ 1.0000000] MIPS32/64 params: TLB entries: 16
[ 1.0000000] MIPS32/64 params: Icache: line=16, total=2048, ways=2,
sets=64, colors=0
[ 1.0000000] MIPS32/64 params: Dcache: line=16, total=2048, ways=2,
sets=64, colors=0
[ 1.0000000] phys segment: 0x8000000 @ 0
[ 1.0000000] adding 0xe000 @ 0x2000 to freelist 0
[ 1.0000000] adding 0x797e000 @ 0x682000 to freelist 0
[ 1.0000000] Enabled early console
[ 1.0000000] Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002,
2003, 2004, 2005,
[ 1.0000000] 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013,
2014, 2015, 2016, 2017,
[ 1.0000000] 2018, 2019, 2020, 2021, 2022
[ 1.0000000] The NetBSD Foundation, Inc.All rights reserved.
[ 1.0000000] Copyright (c) 1982, 1986, 1989, 1991, 1993
[ 1.0000000] The Regents of the University of California.All
rights reserved.
[ 1.0000000] NetBSD 9.3 (LINKITSMART7688) #0: Wed Mar 15 20:37:27 HKT 2023
[ 1.0000000]
luhui@x230.luhui:/home/luhui/pub/netbsd/src/sys/arch/evbmips/compile/LINKITSMART7688
[ 1.0000000] MT7628
[ 1.0000000] total memory = 128 MB
[ 1.0000000] avail memory = 120 MB
[ 1.0000000] mainbus0 (root): Mediatek MT7628 System Bus
[ 1.0000000] cpu0 at mainbus0: 580.00MHz (hz cycles = 2900000, delay
divisor = 290)
[ 1.0000000] cpu0: MIPS 24KE (0x19600) Rev. 0 with software emulated
floating point
从flash镜像启动
我了解了一下mt7628的启动流程,发现从flash启动的流程很简单,但是会遇到一些问题:
取指令太慢, 因为QEMU没有实现cache, 所以启动时的指令是从flash反复读取的,延迟很大.
导致DRAM test和 LZMA解压会很慢, 建议使用hexedit修改镜像来跳过这些指令,或者直接拷贝他们到DRAM上,设置pc寄存器跳过去执行.
你需要从真实的板子上dump flash镜像,然后执行:
./qemu/qemu-system-mipsel -M mt7628 \
-serial telnet:localhost:4000,server \
-serial telnet:localhost:4001,server \
-serial telnet:localhost:4002,server \
-drive if=mtd,file=flash_16M.bin,type=raw \
-usb
本文为项目原作者投稿，原文: https://newluhux.github.io/2023-02-14-qemu-emulate-mt7628.html
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