Slackers,
I had updated the
Virtualbox to version
6.1.36 on
Slackware-15.0-x86_64 host machine.
Now I setup fresh Slackware-15.0-x86_64 on VM (just for testing purpose). After that I installed only two packages (with the help of Slackbuilds from
ppr:kut Current repo) ie.
virtualbox-addons-6.1.36-x86_64-1
virtualbox-kernel-6.1.36_5.15.19-x86_64-1
After that
VMSVGA driver start showing full screen resolution display mode. Before that also I had NO issue with
VBOXSVGA driver.
I have NOT installed Guest Addition from Virtualbox Guest Addition ISO.
Now It works good without any issue.
Thanks ppr:kut for repo.
Thanks Slackers for all suggestions and replies ...