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Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults |
Date: |
Thu, 14 May 2015 14:53:17 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 |
On 14/05/2015 14:45, Markus Armbruster wrote:
> Paolo Bonzini <address@hidden> writes:
>
>> On 14/05/2015 14:02, Markus Armbruster wrote:
>>> It should certainly be off for pc-q35-2.4 and newer. Real Q35 boards
>>> commonly don't have an FDC (depends on the Super I/O chip used).
>>>
>>> We may want to keep it off for pc-i440fx-2.4 and newer. I doubt
>>> there's a real i440FX without an FDC, but our virtual i440FX is quite
>>> unlike a real one in other ways already.
>>
>> That would break libvirt for people upgrading from 2.3 to 2.4. So it's
>> more like pc-i440fx-3.0 and pc-q35-3.0.
>
> What exactly breaks when?
libvirt expects "-nodefaults -drive if=none,id=fdd0,... -global
isa-fdc.driveA=fdd0" to result in a machine with a working FDD. It
doesn't know that it has to add "-machine fdc=on".
Besides, adding a new machine option is not the best we can do. If the
default is "no FDC", all that is needed to add one back is -device. An
FDC is yet another ISA device, it is possible to create one with -device.
> add the magic to make -global isa-fdc... auto-set the option to on.
That would be ugly magic.
The more I think about this, the more I think this is just a kneejerk
reaction to a sensationalist announcement. The effect of this
vulnerability on properly configured data centers (running
non-prehistoric versions of Xen or KVM and using
stubdom/SELinux/AppArmor properly) should be really close to zero.
It's a storm in a tea cup.
Paolo
>> Unless for q35 we decide to
>> break everything and retroactively nuke the controller.
>>
>> (I'm still not sure why we have backwards-compatible machine types for q35).
>
> Beats me :)
>
> [...]
>
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, (continued)
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Daniel P. Berrange, 2015/05/13
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Stefano Stabellini, 2015/05/13
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, John Snow, 2015/05/13
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Stefano Stabellini, 2015/05/14
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Daniel P. Berrange, 2015/05/14
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Michael S. Tsirkin, 2015/05/14
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Markus Armbruster, 2015/05/14
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Paolo Bonzini, 2015/05/14
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Markus Armbruster, 2015/05/14
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Daniel P. Berrange, 2015/05/14
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults,
Paolo Bonzini <=
- Re: [Qemu-devel] [Xen-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Sander Eikelenboom, 2015/05/14
- Re: [Qemu-devel] [Xen-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Daniel P. Berrange, 2015/05/14
- Re: [Qemu-devel] [Xen-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Paolo Bonzini, 2015/05/14
- Re: [Qemu-devel] [Xen-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Stefano Stabellini, 2015/05/14
- Re: [Qemu-devel] [Xen-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Paolo Bonzini, 2015/05/14
- Re: [Qemu-devel] [Xen-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Stefano Stabellini, 2015/05/14
- Re: [Qemu-devel] [Xen-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Michael S. Tsirkin, 2015/05/14
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Michael S. Tsirkin, 2015/05/14
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, John Snow, 2015/05/14
- Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults, Markus Armbruster, 2015/05/15