K 10
svn:author
V 8
dumbbell
K 8
svn:date
V 27
2015-03-01T12:54:22.303830Z
K 7
svn:log
V 546
vt(4): Add support to "downgrade" from eg. vt_fb to vt_vga

The main purpose of this feature is to be able to unload a KMS driver.

When going back from the current vt(4) backend to the previous backend,
the previous backend is reinitialized with the special VDF_DOWNGRADE
flag set. Then the current driver is terminated with the new "vd_fini"
callback.

In the case of vt_fb and vt_vga, this allows the former to pass the
vgapci device vt_fb used to vt_vga so the device can be rePOSTed.

Differential Revision:	https://reviews.freebsd.org/D687

END