option('slirp', type: 'feature', value: 'auto',
description: 'libslirp user mode network backend support')
option('vde', type : 'feature', value : 'auto',
option('slirp', type: 'feature', value: 'auto',
description: 'libslirp user mode network backend support')
option('vde', type : 'feature', value : 'auto',