Reading about video driver support in FreeBSD, I came across this page:
https://wiki.freebsd.org/Graphics/WITH_NEW_XORG

From what I can understand reading the above page, it seems that all current video drivers are KMS driver, and that consequently "vt" should be
adopted instead of "syscons".

One problem that arise when continuing to use syscons with KMS driver is that switching between GUI and console (ALT + Fn) doesn't work, similarly upon shutdown the screen is blacked or corrupted, like I was able to experience myself on one system using AMD/ATI card.

I'm not sure the info linked above are accurate, specifically Xorg version 1.14 which is the version shipped with 10.1, is not mentioned.

Further, the wiki page related to newcons/vt show the difference between the two console implementations:
https://wiki.freebsd.org/Newcons

The two most important things I can see are about:
- unsupported vesa mode inb "vt"
- limited support for splash screen

Now one question arise: should we switch to "vt" or stick with the current "syscons" ?
Or. do I have misunderstood the whole ?

I just noticed that the Beta2 ISO boot using "vt" drivers, but once installed is use the old "syscons".

Looking into I have found that the "vt" console is enabled from a grub settings ("kFreeBSD.kern.vty=vt"), the installed system instead use the classic boot loader (which I believe is named BTX, not sure) and this explain why the installed system doesn't make use of "vt".

Difference I have noticed using "vt":
- when using radeonkms for Xorg vt it behaves correctly i.e. switching to and from vt consoles (CTRL + ALT + Fn), similarly it work correctly upon shutdown when Xorg terminate and the shutdown sequence continue in text mode.

Instead, using radeonkms + syscons, lead to a garbled/corrupted screen, both switching to vty console and upon shutdown.

Drawbacks: some utility doesn't behave correctly, i.e. "kbdmap" show some unrecognized text ... this need to be investigated.

I will test other systems in the following days, so far it appear that "vt" work better when coupled with kms video drivers.

One question: how/where must be placed that kernel setting "kern.vty=vt"when using BTX on an installed system ?

ASX wrote:One question: how/where must be placed that kernel setting "kern.vty=vt"when using BTX on an installed system ?

In loader.conf(5):
hw.vga.textmode=1
kern.vty=vt

see man vt for details.