improve qemu tooling, and document it

This commit is contained in:
Daniel Barlow 2022-09-24 21:03:26 +01:00
parent aa589e8d6b
commit 8dd7bb958a
4 changed files with 69 additions and 11 deletions

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@ -32,11 +32,53 @@ you plan to install onto it. For example:
`outputs.default` is intended to do something appropriate for the
device, whatever that is. For the qemu device, it creates a directory
containing a squashfs root image and a kernel, with which you could
then run
containing a squashfs root image and a kernel.
./run-qemu.sh result/vmlinux result/squashfs
## QEMU
QEMU is useful for developing userland without needing to keep
flashing or messing with U-Boot: it also enables testing against
emulated network peers using [QEMU socket networking](https://wiki.qemu.org/Documentation/Networking#Socket),
which may be preferable to letting Liminix loose on your actual LAN.
We have some tooling to make this easier.
### Networks
We observe these conventions for QEMU network sockets, so that we can
run multiple emulated instances and have them wired up to each other
in the right way
* multicast 230.0.0.1:1234 : access (interconnect between router and "isp")
* multicast 230.0.0.1:1235 : lan
* multicast 230.0.0.1:1236 : world (the internet)
### Running instances
`./scripts/run-qemu.sh` accepts a kernel vmlinux image and a squashfs
and runs qemu with appropriate config for two ethernet interfaces
hooked up to "lan" and "access" respectively. It connects the Liminix serial console
and the [QEMU monitor](https://www.qemu.org/docs/master/system/monitor.html) to
stdin/stdout. Use ^P (not ^A) to switch to the monitor.
If you run with `--background /path/to/unix/socket` it will fork into
the background and open a Unix socket at that pathname to communicate
on. Use `./scripts/connect-qemu.sh` to connect to it, and ^O to
disconnect.
### Emulated upstream connection
In the tests/support/ppp-server directory there are instructions and a script
to configure [Mikrotik RouterOS](https://mikrotik.com/software) as
a PPPoE access concentrator connected to the `access` and `world`
networks, so that Liminix PPPoE client support can be tested.
_Liminix does not provide RouterOS licences and it is your own
responsibility if you use this to ensure you're compliant with
the terms of Mikrotik's licencing._
This may be supplemented or replaced in time with configuurations for
RP-PPPoE and/or Accel PPP.
## Running tests

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@ -1,8 +0,0 @@
#!/usr/bin/env nix-shell
#! nix-shell -i bash -p qemu
qemu-system-mips \
-M malta -m 256 \
-append "default console=ttyS0,38400n8 panic=10 oops=panic init=/bin/init loglevel=8 root=/dev/vda" \
-drive file=$2,format=raw,readonly,if=virtio \
-kernel $1 -nographic -display none -serial mon:stdio

2
scripts/connect-qemu.sh Executable file
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@ -0,0 +1,2 @@
#!/usr/bin/env sh
nix-shell -p socat --run "socat -,raw,echo=0,icanon=0,isig=0,icrnl=0,escape=0x0f unix-connect:$1"

22
scripts/run-qemu.sh Executable file
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@ -0,0 +1,22 @@
#!/usr/bin/env nix-shell
#! nix-shell -i bash -p qemu
if test "$1" = "--background" ; then
socket=$2
echo "running in background, socket is $socket"
flags="--daemonize -chardev socket,id=sock,path=$2,server=on,wait=off,mux=on -mon chardev=sock,mode=readline -serial chardev:sock "
shift;shift
else
flags="-serial mon:stdio"
fi
qemu-system-mips \
-M malta -m 256 \
-echr 16 \
-append "default console=ttyS0,38400n8 panic=10 oops=panic init=/bin/init loglevel=8 root=/dev/vda" \
-drive file=$2,format=raw,readonly=on,if=virtio \
-netdev socket,id=access,mcast=230.0.0.1:1234 \
-device virtio-net-pci,disable-legacy=on,disable-modern=off,netdev=access,mac=ba:ad:1d:ea:21:02 \
-netdev socket,id=lan,mcast=230.0.0.1:1235 \
-device virtio-net-pci,disable-legacy=on,disable-modern=off,netdev=lan,mac=ba:ad:1d:ea:21:01 \
-kernel $1 -display none $flags