[Qemu-devel] Re: [kvm-devel] Feedback and errors

[Avi Kivity <avi@qumranet.com>]

nadim khemir wrote:
> Hi, great work.
>
> While playing with kvm-qemu I noticed a few points that might be of interrest:
>
> 1/ -loadvm and -snapshot don't work together. It works as if -loadvm wasn't 
> passed as argument
>
> 2/ two instances of kvm can be passed the same -hda. There is no locking 
> whatsoever. This messes up things seriously.
>
>   

These two are upstream qemu problems. Copying qemu-devel.

I guess using file locking by default would improve the situation, and 
we can add a -drive ...,exclusive=no option for people playing with 
cluster filesystems.

> 3/ trying to run 'savevm' in the qemu console when -usb is used results in
>
> (qemu) savevm scite
> (qemu) exception 13 (0)
> rax 0000000000000000 rbx 0000000000000000 rcx 0000000000000010 rdx 
> 0000000000000000
> ...
>
> This is documented but a warning in the console would be better than a crash
>
> if the vm is stopped first, 'savevm' works but it still crashes on 'cont' 
> instead
>
> 4/ if -vga-std is used when doing a 'savevm', 'loadvm' restores a black 
> screen. Everything is there and with some gymnastic (moving a window around) 
> the screen is like it should be.
>
> 5/ -usbdevice tablet is a must, 'ctl+alt' is just too painfull! is it possible 
> to get the same effect (with another system) and still be able to 'savevm'?
>
>   

-vmmouse will work with Linux, with Windows, you might need to install a 
driver.

> 6/ If you use -usbdevice tablet, keyboard is first handled by guest OS. In my 
> case I have 'alt F4' close windows in the host OS. If I try to close a window 
> in the guest OS with 'alt f4', it closes qemu altogether.
>   

Try full screen mode (alt-ctrl-F).

If the host didn't handle Alt-F4 in non-capture mode, you'd have no way 
to close the qemu window.

> 7/ On the other hand, mouse events are _not_ handled by the gues OS first, IE: 
> alt click isn't handled by X but by windows (in this case)
>
> 8/ keyboard input lost when switching to full screen or back. fixed by 
> using 'ctl+alt' twice
>
> 9/ IMHO, the way "versionning" with 'savevm' is done could feel more natural.
>
> first run
>     time ------------------------------> stop VM
>                  ^                          |
>                  |                          |
>                  |                          v
>            savevm state1    automatically save "HEAD" in -hda
>
>
>
> second run
>     time ------------------------------>stop VM
>          ^                                 |
>          |                                 |
>          |                                 v
>    loadvm state1           automatically save "HEAD" in -hda
>                                            ^
>                                            |
>                                 .----------'
>                                 |
>        .-------------------------------------------------.
>        | I believe most people want to save in 'state1'  |
>        | or possibly in 'state2' but few want to         |
>        | override "HEAD"                                 |
>        '-------------------------------------------------'
>
>
> automatically overriding 'state1' feels as wrong as overriding "HEAD". I 
> believe that a -savevm to qemu would be a good idea. If nothing is passed as 
> argument "HEAD" is used. That would preserve "HEAD" and allow saving to a 
> user defined vm snapshot.
>
> 10/ subscription to the mailing list doesn't seem to work
>
>   

What do you mean?

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.