Re: qemu oddness with isolinux vesamenu.c32

["H. Peter Anvin" <hpa@zytor.com>]

Just noticed this post was missing the initial information:

<mdomsch> hpa: your test ISO shows:  vesamenu.c32: attempted DOS system 
call INT 2C 42C4 D00004F0
<mdomsch> when run under latest F9 virt-manager started KVM machine
<mdomsch> hpa, but does _not_ fail as such when run manually with
<mdomsch> sudo qemu-kvm -M pc -m 512 -hda 
/var/lib/libvirt/images/hpa.img -cdrom /var/tmp/boot-fc9-3.70-pre26.iso
<mdomsch> hpa, which means one of these args is probably causing it
<mdomsch> /usr/bin/qemu-kvm -S -M pc -m 512 -smp 1 -name foo -monitor 
pty -boot c -drive 
file=/var/lib/libvirt/images/foo.img,if=ide,index=0,boot=on -drive 
file=,if=ide,media=cdrom,index=2 -net 
nic,macaddr=00:16:3e:13:75:3a,vlan=0 -net 
tap,fd=13,script=,vlan=0,ifname=vnet0 -serial pty -parallel none -usb 
-vnc 127.0.0.1:0 -k en-us



For what it's worth, it's the "boot=on" part that is causing extboot to 
be invoked, which is what is causing the failure.

I have to admit I don't really understand why extboot hooks INT 13h at 
all (why emulate a disk on a system where disks are virtual anyway?), 
but more seriously, it has the problem that:

a) it uses vectors in OS reserved space;
b) it doesn't clean up after itself after giving up and before invoking
    the old INT 19h vector.

	-hpa