On Aug 31, 2015, at 4:26 PM, Max Reitz wrote: > On 31.08.2015 22:13, Programmingkid wrote: >> >> On Aug 29, 2015, at 12:39 PM, Max Reitz wrote: >> >>> On 29.08.2015 17:57, Programmingkid wrote: >>>> >>>> On Aug 29, 2015, at 11:40 AM, Max Reitz wrote: >>>> >>>>> On 27.08.2015 03:05, G 3 wrote: >>>>>> I want to share files between my host and guest computer. A feature I >>>>>> want to add would be a new menu item in the Machine menu called "Mount >>>>>> Image File...". When the user selects it, a file open dialog box >>>>>> displays. The user can then select the image file with the file he wants >>>>>> to use. After pushing the OK button, the image file would be mounted >>>>>> like a USB flash drive. This menu item would only show up if there is >>>>>> usb support in the guest machine. >>>>>> >>>>>> Would you be open to accepting such a feature? >>>>> >>>>> Generally I'd expect this to be functionality exposed by the management >>>>> layer. For instance using virt-manager, this can be achived as follows: >>>>> Switch to "Details", then click "Add Hardware", choose "Storage" and >>>>> "USB" as the "Bus type". Choose the image, click "Finish", done. >>>> >>>> Isn't Libvirt only available on Linux? This mount image file feature would >>>> only be on Mac OS X. >>> >>> I'm not sure whether that sounds like a good idea, because then people >>> using bare qemu on Linux would complain that it isn't available with >>> Gtk. So if this was to be implemented, it would have to implemented >>> cross-platform (or at least in a way so it can be used cross-platform >>> later on). >>> >>>> Mac OS X users don't have all the fancy GUI wrappers >>>> for QEMU :( >>> >>> Good thing most GNU/Linux distributions are free. ;-) >>> >>> (sorry, could not resist) >>> >>>> Mac OS X is a second-class citizen in the QEMU world... >>> >>> Might have to do something with most (?) of it being non-free and Apple >>> not caring enough about KVM. >>> >>> (And without KVM, people in turn don't care enough about OS X as a qemu >>> host.) >>> >>> ((But all of that is pretty biased speculation, of course.)) >>> >>>>> The main problem I see with adding this functionality to qemu itself >>>>> would be having to get even further into the GUI business, which hasn't >>>>> worked out too well so far… >>>> >>>> That is because of several reasons. One being maintainers not wanting to >>>> advance the GUI because they feel another program should be QEMU's >>>> GUI. I'm sure there are plenty of good ideas that would advance QEMU's >>>> GUI. These ideas just need to be accepted into QEMU rather than put off. >>> >>> Another is that some people simply feel that qemu should focus on being >>> a backend than having to mess with frontend work, too. See the recent >>> discussion on the Gtk code setting the locale and thus breaking QMP for >>> an example why they have a point. >>> >>> I guess you'll better talk to Markus about this. :-) >>> >>> Quote: "We should've stayed out of the GUI business." >>> >>> (http://lists.nongnu.org/archive/html/qemu-devel/2015-08/msg03049.html) >>> >>>>> If we didn't care about that, than we'd have to think about the >>>>> implementation. Internally, we'd probably call QMP's blockdev-add to >>>>> open the image file, and then QMP's device_add to add the USB device. So >>>>> then qemu would use its own management interfaces to execute the >>>>> operation, which seems a bit strange to me, further hinting at the fact >>>>> that we probably should leave this to the management layer. >>>> >>>> What works does, and it isn't always as nice looking >>>> as we want it. I am sure we will use some kind of API to implement this >>>> feature. >>> >>> Having to deal with ugly legacy cruft from time to time, I don't know >>> whether "What works, works" is always appropriate. >>> >>>> I just wish there were an easy way to share files between the host and the >>>> guest. >>> >>> I don't think using emulated USB storage is the right way to do this, >>> though. Stefan is working on file sharing using NFS over virtio-vsock, >>> which seems more appropriate. But then again I don't whether >>> virtio-vsock will work with an OS X host… >>> >>> === >>> >>> OK, if you really want to implement it, I'm certainly not the right one >>> to stop you, so here is how I'd do it: >>> >>> My "BlockBackend and media" series rewrites the "change" HMP/QMP command >>> to be a macro, basically, that actually executes four lower-level QMP >>> commands. So this means we have a precedent of "macro" QMP commands, and >>> this could be extended. So you could add a "macro" QMP command >>> "usb-storage-insert-file" or something which executes blockdev-add + >>> device_add (if that works).* >>> >>> Then, if I felt really fancy, I'd add some layer which allows >>> generically executing QMP commands through the GUI, based on a whitelist >>> of commands. Each parameter would have to be requested through some GUI >>> interface, for instance, filenames would be queried through an >>> appropriate dialog. Ideally, this would be GUI-agnostic, but this may >>> not be reasonably possible. >>> >>> Then you'd whitelist usb-storage-insert-file (or however it is named), >>> give it some nice alias and you'd be done. >>> >>> While this would be much work I feel like this would actually be the >>> nicest solution. >>> >>> This is just a very rough outline, though, and since it somehow goes >>> against everything qemu's GUI was used for so far (just the most basic >>> things, basically nothing about controlling the VM except for >>> Pause/Shutdown/Reboot) I have no idea how it would be received. >>> >>> Max >>> >>> >>> *Actually you'd probably want a generic insert-storage-file which takes >>> the kind of storage device to add as a parameter. >> >> I thought about using add_init_drive() found in device-hotplug.c, >> but it is private. Too bad. It looked perfect. >> >> https://wiki.ubuntu.com/QemuDiskHotplug#Hotplug_USB_Disk >> This page say talks about how to do it. This is what it said to do: >> >> drive_add 0 if=none,id=usbdisk1,file=/tmp/test.img >> >> Then >> >> device_add usb-storage,id=usbdisk1,drive=usbdisk1 >> >> I wasn't able to follow what you said. Do you think you could send me >> an example of how you think I should do the mounting of the image >> file? > > That was the "if that works" part. ;-) > > The following works for me: > > $ echo foo > bar > $ x86_64-softmmu/qemu-system-x86_64 -qmp stdio -usb -cdrom > ~/tmp/archlinux-2015.07.01-dual.iso -enable-kvm -m 512 > {"QMP": {"version": {"qemu": {"micro": 50, "minor": 4, "major": 2}, > "package": ""}, "capabilities": []}} > {'execute': 'qmp_capabilities'} > {"return": {}} > {'execute': 'blockdev-add', 'arguments': {'options': {'id': 'usb-image', > 'driver': 'raw', 'file': {'driver': 'file', 'filename': 'bar'}}}} > > {"return": {}} > {'execute': 'device_add', 'arguments': {'driver': 'usb-storage', 'id': > 'usb-disk', 'drive': 'usb-image'}} > {"return": {}} > > In the VM, before device_add: > # cat /dev/sda > cat: /dev/sda: No such file or directory > > After device_add: > # cat /dev/sda > foo
Is there a function that the GUI could call to send all of the JSON code as the argument to execute. > Unplugging the device can be done with device_del; but there is no > blockdev-del yet, so the image file will remain lingering. If the user decided to use the same image file again, would that be possible? What about handle_hmp_command() in monitor.c. Would it be ok to send commands to execute?
