Hi, just a few quick thoughts:

Questions:

1) Allow user to set these parameters on Template? Or just for edit

Some host filesystems do not support all disk caching modes (For
example, ZFS does not support cache=none).  When attempting to run a
guest (in a dir-type storage pool) on a host filesystem that does not
support the selected disk caching mode, Kimchi will throw an error and
fail to start the guest.  (reproduced below)

Including disk-caching settings in each template would ensure that the
user does not have to remember to change the disk-cache setting for
every guest.

2)  How i can prevent some error by the user? Example: Windows cannot use iscsi driver. How can i created a dictionary to validate ?

It seems like Kimchi is already good at catching and displaying
configuration errors that would prevent the VM from running.  For the
Windows/iscsi issue, the question (unless I am misunderstanding) seems
to be more general: How hard do you want to try to make sure that the
user has configured the VM settings correctly for their chosen guest
OS.

Thanks!

Error: KCHVM0019E: Unable to start virtual machine zfs-tester.
Details: internal error: process exited while connecting to monitor:
2017-02-09T20:19:07.281748Z qemu-system-x86_64: -drive
file=/tank/virt-storage/f59abc76-b0b4-494b-85d1-7ff7f4a03970-0.img,format=qcow2,if=none,id=drive-virtio-disk0,cache=none:
file system may not support O_DIRECT 2017-02-09T20:19:07.281816Z
qemu-system-x86_64: -drive
file=/tank/virt-storage/f59abc76-b0b4-494b-85d1-7ff7f4a03970-0.img,format=qcow2,if=none,id=drive-virtio-disk0,cache=none:
Could not open '/tank/virt-storage/f59abc76-b0b4-494b-85d1-7ff7f4a03970-0.img':
Invalid argument