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From: Ondrej Zajicek <santiago@mail.cz>
To: linux-fbdev-devel@lists.sourceforge.net
Subject: Two bugs in fbcon?
Date: Mon, 15 May 2006 23:03:10 +0200	[thread overview]
Message-ID: <20060515210310.GA1199@localhost.localdomain> (raw)

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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."

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             reply	other threads:[~2006-05-15 21:03 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-05-15 21:03 Ondrej Zajicek [this message]
2006-05-20  0:30 ` Two bugs in fbcon? Antonino A. Daplas
2006-05-20  1:40   ` Panning in the intelfb driver Dennis Munsie
2006-05-23 21:11   ` Two bugs in fbcon? Ondrej Zajicek
  -- strict thread matches above, loose matches on Subject: below --
2006-05-16 14:07 Ondrej Zajicek

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