Re: [Qemu-devel] [SeaBIOS] [PATCH] don't expose pvpanic device in the UI

[Gerd Hoffmann]

  Hi,

> And what are the rules that govern device exclusion from -nodefaults
> list? Why -nodefaults does not create empty machine?

"qemu -nodefaults" should give you just cpu + northbridge + southbridge.

"qemu" should give you a usable virtual machine, so qemu adds some
optional devices which are (or used to be) standard in a pc: floppy,
cdrom, serial port, parallel port, vga card, nic.

Sometimes things are a bit odd for historical reasons:

USB controllers are only present in case you ask for them via '-usb' or
add them via '-device', even though they are part of the southbridge.

vmport is there unconditionally.  And I'd rather make that one
configurable instead of adding more hard-coded devices.

cheers,
  Gerd