Bug in uninorth-agp.c parsing of module parameter uninorth_agp.aperture

Bug in uninorth-agp.c parsing of module parameter uninorth_agp.aperture

[Jochen Rollwagen]

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Hi,

i found a bug in uninorth-agp.c, function uninorth_fetch_size.

the line

size  <http://lxr.free-electrons.com/ident?i=size>  =memparse  <http://lxr.free-electrons.com/ident?i=memparse>(aperture  <http://lxr.free-electrons.com/ident?i=aperture>, &aperture  <http://lxr.free-electrons.com/ident?i=aperture>) >> 20;

always sets size to zero which makes the driver allocate the default size of 256 MB which is obviously too large for older uninorth revisions.

I split the line into memparse and shifting and inserted diagnostic messages, output with uninorth_agp.aperture = 32 as boot parameter:

Feb 15 19:12:44 mac-mini kernel: [    2.568636] agpgart-uninorth 0000:00:0b.0: size in uninorth_fetch_size after memparse: 32
Feb 15 19:12:44 mac-mini kernel: [    2.568642] agpgart-uninorth 0000:00:0b.0: size after >> 20: 0

It would be nice if a patch could be produced so i can experiment with 
different aperture sizes without having to rebuild the kernel every time :-)

Cheers

Jochen

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Re: Bug in uninorth-agp.c parsing of module parameter uninorth_agp.aperture

[Michel Dänzer]

On 16.02.2015 03:27, Jochen Rollwagen wrote:
> Hi,
> 
> i found a bug in uninorth-agp.c, function uninorth_fetch_size.
> 
> the line
> 
> size = memparse(aperture, &aperture) >> 20;
> 
> always sets size to zero which makes the driver allocate the default
> size of 256 MB which is obviously too large for older uninorth
> revisions.

Sounds like the default should be lower for older UniNorth revisions.
Can you make a patch for that?


> I split the line into memparse and shifting and inserted diagnostic
> messages, output with uninorth_agp.aperture = 32 as boot parameter:
> 
> Feb 15 19:12:44 mac-mini kernel: [    2.568636] agpgart-uninorth
> 0000:00:0b.0: size in uninorth_fetch_size after memparse: 32 Feb 15
> 19:12:44 mac-mini kernel: [    2.568642] agpgart-uninorth
> 0000:00:0b.0: size after >> 20: 0

Following your memparse link to
http://lxr.free-electrons.com/source/lib/cmdline.c#L127 , you can see
that the memparse function supports suffices such as 'M' or 'm'; without
suffix, the size is interpreted as bytes.

So you need something like uninorth_agp.aperture=32m .


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer
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