I've been adapting libvirt to use to the various new QMP commands to
query QEMU's capabilities, instead of the hated -help parsing. Obviously
the critical part of this is being able to reliably start a bare QEMU
process with no actual guest OS configured (no disks, no kernel, etc)
and talk to its monitor. I hadn't anticipated problems since I only
tested with x86_64 / i386 most of the time, which work well in this
respect. Currently I am doing
# $QEMU_BINARY -S \
-no-user-config \
-nodefconfig \
-nodefaults \
-nographic \
-qmp stdio
This works for about 50% of the QEMU targets:
qemu-system-alpha
qemu-system-i386
qemu-system-lm32
qemu-system-ppc
qemu-system-ppc64
qemu-system-s390x
qemu-system-sparc
qemu-system-sparc64
qemu-system-x86_64
qemu-system-xtensa
qemu-system-xtensaeb
but fails for the other 50% of targets:
qemu-system-arm
qemu-system-cris
qemu-system-m68k
qemu-system-mips
qemu-system-mips64
qemu-system-mips64el
qemu-system-mipsel
qemu-system-or32
qemu-system-ppcemb
qemu-system-sh4
qemu-system-sh4eb
qemu-system-unicore32
With the failing targets i see the following kinds of errors:
$ qemu-system-arm -S -nodefconfig -nodefaults -nographic -qmp
unix:/tmp/foo,server,nowait
Kernel image must be specified
$ qemu-system-cris -S -nodefconfig -nodefaults -nographic -qmp
unix:/tmp/foo,server,nowait
Kernel image must be specified
$ qemu-system-m68k -S -nodefconfig -nodefaults -nographic -qmp
unix:/tmp/foo,server,nowait
Kernel image must be specified
$ qemu-system-mips -S -nodefconfig -nodefaults -nographic -qmp
unix:/tmp/foo,server,nowait qemu: Could not load MIPS bios 'mips_bios.bin', and
no -kernel argument was specified
$ qemu-system-mipsel -S -nodefconfig -nodefaults -nographic -qmp
unix:/tmp/foo,server,nowait
qemu: Could not load MIPS bios 'mipsel_bios.bin', and no -kernel argument was
specified
$ qemu-system-or32 -S -nodefconfig -nodefaults -nographic -qmp
unix:/tmp/foo,server,nowait
Can't create serial device, empty char device
$ qemu-system-ppcemb -S -nodefconfig -nodefaults -nographic -qmp
unix:/tmp/foo,server,nowait
Unable to find PowerPC CPU definition
$ qemu-system-sh4 -S -nodefconfig -nodefaults -nographic -qmp
unix:/tmp/foo,server,nowait
Initializing CPU
Allocating ROM
Allocating SDRAM 1
Allocating SDRAM 2
shix_init: load BIOS 'shix_bios.bin'
ret=-1
qemu: could not load SHIX bios 'shix_bios.bin'
$ qemu-system-sh4eb -S -nodefconfig -nodefaults -nographic -qmp
unix:/tmp/foo,server,nowait
Initializing CPU
Allocating ROM
Allocating SDRAM 1
Allocating SDRAM 2
shix_init: load BIOS 'shix_bios.bin'
ret=-1
qemu: could not load SHIX bios 'shix_bios.bin'
$ qemu-system-unicore32 -S -nodefconfig -nodefaults -nographic -qmp
unix:/tmp/foo,server,nowait
qemu-system-unicore32: /home/berrange/src/virt/qemu/hw/unicore32/../puv3.c:81:
puv3_load_kernel: Assertion `kernel_filename != ((void *)0)' failed.
Aborted
Can we "fix" them in some way to not require the kernel ?
Do we have to go down the route of adding some sort of "-no-vm" flag to
explicitly say we don't care about any of the VM setup parts ? This would
be more like what my old patches did which mapped monitors commands
onto '-query-XXXXX' command line args, bypassing VM setup, but still
using normal QMP monitor interaction.
Any other suggestions on how to reliably get a QMP monitor to a target,
without any VM config. ?
Daniel
--
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