Thread (4 messages) 4 messages, 3 authors, 2006-05-23

Two bugs in fbcon?

From: Ondrej Zajicek <hidden>
Date: 2006-05-15 21:03:35

Hello

I found that in  kernel 2.6.16.16 is some very strange behavior in fbcon.
I added some printks to some functions in fbcon and i found this:

I am on vt0, i have active vt0-vt3. When i modprobe fbcon (having fbdev
driver inserted before), functions fbcon.c/fbcon_init() and
fbcon.c/updatescrollmode() are called for each active vt.

Order is:
fbcon_init(vt0)
updatescrollmode(vt0)
updatescrollmode(vt1)
fbcon_init(vt1)
updatescrollmode(vt2)
fbcon_init(vt2)
updatescrollmode(vt3)
fbcon_init(vt3)

for vt1-vt3 updatescrollmode is called before fbcon_init which caused that
associated struct display::vrows value is computed (in updatescrollmode()
- fbcon.c:1970) from old vc->vc_rows (which is updated in fbcon_init()).

Now second strangeness - I am still on vt0 (immediately after modprobe fbcon),
but during calls to bitblit.c/bit_cursor display structure associated with
vt3 is used (in bitblit.c:244 - ops->p). Combined with previous strangeness
(bad vrows values in vt1-vt3) i get cursor visible on bad row.

When i switch to another vt or switch resolution, then this is corrected 
(next calls to bitblit.c/bit_cursor are using correct display structure.).

I don't understand fbcon enough to correct this problem (and be sure not to
make some other :-)).

-- 
Elen sila lumenn' omentielvo

Ondrej 'SanTiago' Zajicek (email: santiago@mail.cz, jabber: santiago@njs.netlab.cz)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."

Attachments

Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help