RE: [Xen-devel] Should Qemu monitor be enabled by default

["You, Yongkang" <yongkang.you@xxxxxxxxx>]

Hi Daniel,

>The '-monitor vc' is already the default for QEMU, so both branches of
>that if end up reducing to the same functional state - the monitor being
>enabled. You need to explicitly disable the monitor if the config file
>has monitor=0

Aha. Thanks for checking the patch. It is a typo. In the attachment patch, I 
have changed the monitor default value to 0. 

>
>I'm not sure this patch is a good idea long term though. If, as Anthony
>suggests in previous thread, XenD takes control of the monitor and provides
>an explicit 'xm monitor' command, then it'll be impossible to also make
>the monitor also appear on a VC.

Yes. It is not a long term solution like previous discussion. But 3.0.5 is 
near, we had better to use the interim method. 

>
>This also doesn't address the issue that making the monitor appear on a
>VC is fundamentally a security risk and so can never be enabled in any
>production environment where you care about integrity of the Dom0 host.
>I don't see the point in introducing a config file setting which will
>have to go away once a sustainable 'xm monitor' patch is implemented.
>
>For the timescales involved in 3.0.5 I think we should instead make sure
>that 'xm block-configure' works correctly.

Yes. I agree it has potential security issue. But from the original concern 
email, I just knew the cdrom option would cause possible normal user to write 
file as root privilege. But actually if we could assign 'readonly' permission 
for cdrom option, nobody could write the system file. But still have read 
permission security issue. 

Well, users are familiar with Qemu Monitor for a long time. And although we can 
use xm command to change the CD-ROM file, we hardly switch HVM console to ttyN 
or call HVM by "ctrl-alt-N" (monitor can send short keys to HVM). So if simply 
remove Monitor function, it would also lose an important function of HVM. IMHO, 
virtualization production would drop it. :) So we create such patch to do a 
compromise workaround and let user to choose. 

Best Regards,
Yongkang (Kangkang) 永康

Attachment: qemu_monitor.patch
Description: qemu_monitor.patch

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