Two bugs in fbcon?

Two bugs in fbcon?

[Ondrej Zajicek]

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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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Two bugs in fbcon?

[Ondrej Zajicek]

(i resent this email as previous one seems to be lost, so i am sorry
in case you get both ones)

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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Re: Two bugs in fbcon?

[Antonino A. Daplas]

Ondrej Zajicek wrote:
> 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 :-)).
> 

Might be fixed in Linus's latest git tree.  Try applying this changeset:

http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=1a37d5f51020b9967d4b4094f6d627d0873a6469

Tony



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Panning in the intelfb driver

[Dennis Munsie]

has anyone here actually been able to use the panning support in the  
intelfb driver?  we are having some issues using it, and my quick  
perusal of the code leads me to believe that it might not actually work.

dennis


-------------------------------------------------------
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Re: Two bugs in fbcon?

[Ondrej Zajicek]

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On Sat, May 20, 2006 at 08:30:06AM +0800, Antonino A. Daplas wrote:
> Ondrej Zajicek wrote:
> > 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.
> 
> Might be fixed in Linus's latest git tree.  Try applying this changeset:
> 
> http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=1a37d5f51020b9967d4b4094f6d627d0873a6469
> 
> Tony

Yes, this corrects it. Thank you.

-- 
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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