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qemumonitor: fix for qemu v2.12

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Must use expect now for some reason, and I only know how to make it work
nicely if the arguments come from CLI arguments instead of stdin.

Document it on a dedicated section.

Fix #29
This commit is contained in:
Ciro Santilli
2018-05-26 22:12:36 +01:00
parent fe01ade54d
commit bad30f513c
3 changed files with 94 additions and 35 deletions
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99
README.adoc
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@@ -228,32 +228,9 @@ https://superuser.com/questions/1087859/how-to-quit-the-qemu-monitor-when-not-us
Alternative methods:
* `echo quit | ./qemumonitor`
* `Ctrl-A C` then `quit`
* `quit` command on the <<qemu-monitor>>
* `pkill qemu`
Toggle between QEMU monitor and the shell:
....
Ctrl-A C
....
* http://stackoverflow.com/questions/14165158/how-to-switch-to-qemu-monitor-console-when-running-with-curses
* https://superuser.com/questions/488263/how-to-switch-to-the-qemu-control-panel-with-nographics
But doing:
....
echo quit | ./qemumonitor
....
is generally more practical since you can use host shell functionality like shell history.
Getting everything to work requires careful choice of QEMU command line options:
* https://stackoverflow.com/questions/49716931/how-to-run-qemu-with-nographic-and-monitor-but-still-be-able-to-send-ctrlc-to/49751144#49751144
* https://unix.stackexchange.com/questions/167165/how-to-pass-ctrl-c-to-the-guest-when-running-qemu-with-nographic/436321#436321
TODO: if you hit `Ctrl-C` several times while `arm` or `aarch64` are booting, after boot the userland shell does not show any updates when you type, this seems to be a bug on the Linux kernel v4.16: http://lists.nongnu.org/archive/html/qemu-discuss/2018-04/msg00027.html
=== Graphic mode
@@ -280,7 +257,7 @@ Text mode has the following limitations over graphics mode:
`x86_64` has a VGA device enabled by default, as can be seen as:
....
echo 'info qtree' | ./qemumonitor
./qemumonitor info qtree
....
and the Linux kernel picks it up through the link:https://en.wikipedia.org/wiki/Linux_framebuffer[fbdev] graphics system as can be seen from:
@@ -2898,6 +2875,12 @@ which shows:
so only `1` has `myirqhandler0` attached but not `0`.
The <<qemu-monitor>> also has some interrupt statistics for x86_64:
....
./qemumonitor info irq
....
TODO: properly understand how each IRQ maps to what number.
==== dummy-irq
@@ -3757,7 +3740,7 @@ and run:
On another shell, take a snapshot:
....
echo 'savevm my_snap_id' | ./qemumonitor
./qemumonitor savevm my_snap_id
....
The counting continues.
@@ -3765,7 +3748,7 @@ The counting continues.
Restore the snapshot:
....
echo 'loadvm my_snap_id' | ./qemumonitor
./qemumonitor loadvm my_snap_id
....
and the counting goes back to where we saved. This shows that CPU and memory states were reverted.
@@ -3785,7 +3768,7 @@ echo 0 >f
Monitor:
....
echo 'savevm my_snap_id' | ./qemumonitor
./qemumonitor savevm my_snap_id
....
Guest:
@@ -3797,7 +3780,7 @@ echo 1 >f
Monitor:
....
echo 'loadvm my_snap_id' | ./qemumonitor
./qemumonitor loadvm my_snap_id
....
Guest:
@@ -3965,7 +3948,7 @@ which we identify as being `edu` and `pci_min` respectively by the magic numbers
Alternatively, we can also do use the QEMU monitor:
....
echo 'info qtree' | ./qemumonitor
./qemumonitor info qtree
....
which gives:
@@ -4562,6 +4545,62 @@ The current FAQ says it is not possible to use dynamic executables: http://gem5.
but I could not find how to actually use it.
=== QEMU monitor
The QEMU monitor is a terminal that allows you to send text commands to the QEMU VM: https://en.wikibooks.org/wiki/QEMU/Monitor
Accessed it in either <<text-mode>> and <<graphic-mode>>:
....
./qemumonitor
....
or send one command such as `info qtree` and quit the monitor:
....
./qemumonitor info qtree
....
Source: link:qemumonitor[]
`qemumonitor` uses the `-monitor` QEMU command line option, which makes the monitor listen from a socket.
`qemumonitor` does not support input from an stdin pipe currently, see comments on the source for rationale.
Alternatively, from text mode:
....
Ctrl-A C
....
and go back to the terminal with:
....
Ctrl-A C
....
* http://stackoverflow.com/questions/14165158/how-to-switch-to-qemu-monitor-console-when-running-with-curses
* https://superuser.com/questions/488263/how-to-switch-to-the-qemu-control-panel-with-nographics
And in graphic mode from the GUI:
....
Ctrl-Alt ?
....
where `?` is a digit `1`, or `2`, or, `3`, etc. depending on what else is available on the GUI: serial, parallel and frame buffer.
In general, `./qemumonitor` is the best option, as it:
* works on both modes
* allows to use the host Bash history to re-run one off commands
* allows you to search the output of commands on your host shell even when in graphic mode
Getting everything to work required careful choice of QEMU command line options:
* https://stackoverflow.com/questions/49716931/how-to-run-qemu-with-nographic-and-monitor-but-still-be-able-to-send-ctrlc-to/49751144#49751144
* https://unix.stackexchange.com/questions/167165/how-to-pass-ctrl-c-to-the-guest-when-running-qemu-with-nographic/436321#436321
=== Debug the emulator
When you start hacking QEMU or gem5, it is useful to see what is going on inside the emulator themselves.