[QUESTION] qemu: how to control the switch of floppy drive

[QUESTION] qemu: how to control the switch of floppy drive

[Xu, Yanfei]

Hi experts,

How can I disable the floppy controller drive when I boot a VM by qemu-
system-x86_64? I did not specify any arguments about floppy, but after
the qemu boots up, linux always can detect floppy drive and then
modprobe the matched floppy.ko.

qemu version: v5.2

command line:

qemu-system-x86_64 -device virtio-net-
pci,netdev=net0,mac=52:54:00:12:34:02 -netdev
tap,id=net0,ifname=tap0,script=no,downscript=no -object rng-
random,filename=/dev/urandom,id=rng0 -device virtio-rng-pci,rng=rng0
-drive file=/path/to/images/qemux86-64
/qemux86-64.ext4,if=virtio,format=raw -usb -device usb-tablet   -cpu
core2duo -enable-kvm -m 512  -pidfile /path/to/pidfile_4167420 -m 512
-snapshot -serial mon:vc -serial null  -kernel /path/to/qemux86-64
/bzImage.bin -append 'root=/dev/vda rw  mem=512M
ip=192.168.7.2::192.168.7.1:255.255.255.0 oprofile.timer=1
printk.time=1'

As I konw BIOS can control the switch of floppy controller on a real
hardware, But how can I do it on qemu? And does the qemu enable that by
default?


Thanks,
Yanfei

Re: [QUESTION] qemu: how to control the switch of floppy drive

[Philippe Mathieu-Daudé]

Hi,

On 4/9/21 8:48 AM, Xu, Yanfei wrote:
> How can I disable the floppy controller drive when I boot a VM by qemu-
> system-x86_64? I did not specify any arguments about floppy, but after
> the qemu boots up, linux always can detect floppy drive and then
> modprobe the matched floppy.ko.
> 
> qemu version: v5.2
> 
> command line:
> 
> qemu-system-x86_64 -device virtio-net-
> pci,netdev=net0,mac=52:54:00:12:34:02 -netdev
> tap,id=net0,ifname=tap0,script=no,downscript=no -object rng-
> random,filename=/dev/urandom,id=rng0 -device virtio-rng-pci,rng=rng0
> -drive file=/path/to/images/qemux86-64
> /qemux86-64.ext4,if=virtio,format=raw -usb -device usb-tablet   -cpu
> core2duo -enable-kvm -m 512  -pidfile /path/to/pidfile_4167420 -m 512
> -snapshot -serial mon:vc -serial null  -kernel /path/to/qemux86-64
> /bzImage.bin -append 'root=/dev/vda rw  mem=512M
> ip=192.168.7.2::192.168.7.1:255.255.255.0 oprofile.timer=1
> printk.time=1'
> 
> As I konw BIOS can control the switch of floppy controller on a real
> hardware, But how can I do it on qemu? And does the qemu enable that by
> default?

See
https://gitlab.com/qemu-project/qemu/-/blob/master/docs/qdev-device-use.txt#L105

* if=floppy

  -device floppy,unit=UNIT,drive=DRIVE-ID

  Without any -device floppy,... you get an empty unit 0 and no unit
  1.  You can use -nodefaults to suppress the default unit 0, see
  "Default Devices".

Regards,

Phil.

Re: [QUESTION] qemu: how to control the switch of floppy drive

[Xu, Yanfei]

On 4/9/21 3:10 PM, Philippe Mathieu-Daudé wrote:
> [Please note: This e-mail is from an EXTERNAL e-mail address]
> 
> Hi,
> 
> On 4/9/21 8:48 AM, Xu, Yanfei wrote:
>> How can I disable the floppy controller drive when I boot a VM by qemu-
>> system-x86_64? I did not specify any arguments about floppy, but after
>> the qemu boots up, linux always can detect floppy drive and then
>> modprobe the matched floppy.ko.
>>
>> qemu version: v5.2
>>
>> command line:
>>
>> qemu-system-x86_64 -device virtio-net-
>> pci,netdev=net0,mac=52:54:00:12:34:02 -netdev
>> tap,id=net0,ifname=tap0,script=no,downscript=no -object rng-
>> random,filename=/dev/urandom,id=rng0 -device virtio-rng-pci,rng=rng0
>> -drive file=/path/to/images/qemux86-64
>> /qemux86-64.ext4,if=virtio,format=raw -usb -device usb-tablet   -cpu
>> core2duo -enable-kvm -m 512  -pidfile /path/to/pidfile_4167420 -m 512
>> -snapshot -serial mon:vc -serial null  -kernel /path/to/qemux86-64
>> /bzImage.bin -append 'root=/dev/vda rw  mem=512M
>> ip=192.168.7.2::192.168.7.1:255.255.255.0 oprofile.timer=1
>> printk.time=1'
>>
>> As I konw BIOS can control the switch of floppy controller on a real
>> hardware, But how can I do it on qemu? And does the qemu enable that by
>> default?
> 
> See
> https://gitlab.com/qemu-project/qemu/-/blob/master/docs/qdev-device-use.txt#L105
> 
> * if=floppy
> 
>    -device floppy,unit=UNIT,drive=DRIVE-ID
> 
>    Without any -device floppy,... you get an empty unit 0 and no unit
>    1.  You can use -nodefaults to suppress the default unit 0, see
>    "Default Devices".

I see. Thanks for your link and detailed explanation. :)

Thanks,
Yanfei

> 
> Regards,
> 
> Phil.
> 

Re: [QUESTION] qemu: how to control the switch of floppy drive

[Markus Armbruster]

"Xu, Yanfei" <yanfei.xu@windriver.com> writes:

> Hi experts,
>
> How can I disable the floppy controller drive when I boot a VM by qemu-
> system-x86_64? I did not specify any arguments about floppy, but after
> the qemu boots up, linux always can detect floppy drive and then
> modprobe the matched floppy.ko.
>
> qemu version: v5.2
>
> command line:
>
> qemu-system-x86_64 -device virtio-net-
> pci,netdev=net0,mac=52:54:00:12:34:02 -netdev
> tap,id=net0,ifname=tap0,script=no,downscript=no -object rng-
> random,filename=/dev/urandom,id=rng0 -device virtio-rng-pci,rng=rng0
> -drive file=/path/to/images/qemux86-64
> /qemux86-64.ext4,if=virtio,format=raw -usb -device usb-tablet   -cpu
> core2duo -enable-kvm -m 512  -pidfile /path/to/pidfile_4167420 -m 512
> -snapshot -serial mon:vc -serial null  -kernel /path/to/qemux86-64
> /bzImage.bin -append 'root=/dev/vda rw  mem=512M
> ip=192.168.7.2::192.168.7.1:255.255.255.0 oprofile.timer=1
> printk.time=1'
>
> As I konw BIOS can control the switch of floppy controller on a real
> hardware, But how can I do it on qemu? And does the qemu enable that by
> default?

Machine types pc-i440fx-* provide a floppy controller.  An empty floppy
drive is connected by default.  Use -nodefaults to suppress it.

Machine types pc-q35-* provide a floppy controller only when you ask for
it, e.g. with -drive if=floppy.

Use -M to select the machine type.

Re: [QUESTION] qemu: how to control the switch of floppy drive

[Xu, Yanfei]

On 4/9/21 4:19 PM, Markus Armbruster wrote:
> Machine types pc-i440fx-* provide a floppy controller.  An empty floppy
> drive is connected by default.  Use -nodefaults to suppress it.
> 
> Machine types pc-q35-* provide a floppy controller only when you ask for
> it, e.g. with -drive if=floppy.
> 
> Use -M to select the machine type.

Got it. Thanks a lot!  :)

Thanks,
Yanfei