Bug#732514: [PATCH] fixes for Radeon KMS on kFreeBSD

[Alex Deucher]

On Wed, Dec 18, 2013 at 4:18 PM, Robert Millan <rmh at debian.org> wrote:
> On 18/12/2013 22:09, Julien Cristau wrote:
>> On Wed, Dec 18, 2013 at 22:05:27 +0100, Robert Millan wrote:
>>
>>> Besides, when it comes to KMS drivers, is there a point in auto-loading them
>>> just because the hardware is present? AFAICS it makes a lot more sense to load
>>> them only when X is started and we know we will need them.
>>>
>> Yes.  At least on linux it also gives you the fb console.
>
> Oh. Well we don't enable that yet (but now that you mention it, maybe we
> should...).
>
>> And there's
>> been a number of bug reports where X failed to start because the radeon
>> kernel driver was loaded too late.
>
> Where's this race condition? Is it related to the Linux plumbing, or something
> that could affect us too?

It could affect you too.  With UMS, the ddx would load the kernel
driver, but the kernel driver didn't actually do anything until the
ddx explicitly asked it to something.  With UMS, the ddx still took
care of hw init, the kernel driver basically just managed dma
addresses.  With KMS, the kernel driver inits and manages the hw so it
takes relatively longer to load and the ddx may try and access the
kernel driver before it's finished loading leading to fail.

Alex

>
> --
> Robert Millan
>
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