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https://github.com/kholia/mips-hacking
Notes on QEMU and Debian MIPS (big-endian)
https://github.com/kholia/mips-hacking
Last synced: 1 day ago
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Notes on QEMU and Debian MIPS (big-endian)
- Host: GitHub
- URL: https://github.com/kholia/mips-hacking
- Owner: kholia
- Archived: true
- Created: 2017-06-22T14:12:53.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2018-11-12T04:42:15.000Z (about 6 years ago)
- Last Synced: 2024-08-02T07:02:17.855Z (3 months ago)
- Language: Python
- Homepage:
- Size: 26.4 KB
- Stars: 42
- Watchers: 8
- Forks: 13
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
#### (UPDATE) Easily start a MIPS VM with arm_now
```sh
$ pip3 install --user https://github.com/nongiach/arm_now/archive/master.zip --upgrade
$ arm_now start mips32
Welcome to Buildroot
buildroot login: root
# uname -m
mips
# gdb /bin/ls
(gdb) start
Temporary breakpoint 1, 0x00405434 in main ()
(gdb) x/i $pc
=> 0x405434 : li a0,-1
```
Note: The `mips32` VM image seems to be pretty limited (no gdb, no
apt-get/opkg). I recommend using the following method for getting a proper
`mips32` image.
#### Get Debian for MIPS
* http://ftp.debian.org/debian/dists/stretch/main/installer-mips/current/images/malta/netboot/
* Download both files.
#### Building QEMU (optional)
```
./configure --prefix=$HOME/QEMU --target-list=mips-softmmu,mips-linux-user
make
make install
```
#### HOWTO
##### Install
```
qemu-img create -f qcow2 hda.img 32G
qemu-system-mips -M malta -m 256 -hda hda.img -kernel vmlinux-4.9.0-3-4kc-malta \
-initrd initrd.gz -append "console=ttyS0 nokaslr" -nographic
```
Copy `initrd.img-4.9.0-3-4kc-malta` from the installed VM to the host machine.
##### Boot:
```
qemu-system-mips -M malta -m 256 -hda hda.img -kernel vmlinux-4.9.0-3-4kc-malta \
-initrd initrd.img-4.9.0-3-4kc-malta \
-append "root=/dev/sda1 console=ttyS0 nokaslr" -nographic \
-netdev user,id=net0 \
-device e1000-82545em,netdev=net0,id=net0,mac=52:54:00:c9:18:27 \
-net user -redir tcp:2222::22
```
`C-a h` key combination is useful to interacting with QEMU in `-nographic` mode.
#### Notes
* Kernel (and initrd.gz) from Debian 9 MIPS (version 20170615) does not boot in
QEMU 2.9.0. It fails with `Initramfs unpacking failed: uncompression error` or
`Initramfs unpacking failed: junk in compressed archive` error messages.
Update: In Debian 9, the initrd load address clashes with kernel address
randomization due to a bug in QEMU. Pass "nokaslr" to the append option.
* Debugging a MIPS binary directly under QEMU,
```
$ qemu-mips -g 1234 ./mips.binary
$ gdb ./mips.binary # in another terminal
(gdb) set architecture mips
(gdb) target remote localhost:1234
```
Run dynamically linked MIPS binary with QEMU,
```
LD_LIBRARY_PATH=. qemu-mips ./routerlocker
```
Check behaviour of a MIPS binary,
```
LD_LIBRARY_PATH=. qemu-mips -strace ./routerlocker
```
#### References
* https://people.debian.org/~aurel32/qemu/mips/
* https://gmplib.org/~tege/qemu.html
* http://toolchains.free-electrons.com/
* https://en.wikibooks.org/wiki/QEMU/Networking
* https://github.com/kholia/kernel-configs
#### Thanks
* rofl0r
* aurel32