Well, it is late Saturday here. I know everyone is busy, but can at least
someone confirm that they know the answer but just don't have time for it ?
I'd hate to lose a weekend waiting for something that's not going to
come..
Vladimir Dergachev
---------- Forwarded message ----------
Date: Wed, 10 Oct 2001 18:08:50 -0400 (EDT)
From: [EMAIL PROTECTED]
To: Keith Whitwell <[EMAIL PROTECTED]>
Cc: [EMAIL PROTECTED]
Subject: Re: [Dri-devel] Using drm (fwd)
On Wed, 10 Oct 2001, Keith Whitwell wrote:
> On Wed, 10 Oct 2001 15:45, [EMAIL PROTECTED] wrote:
> > On Wed, 10 Oct 2001, Daryll Strauss wrote:
> > > On Wed, Oct 10, 2001 at 05:13:40PM -0400, [EMAIL PROTECTED] wrote:
> > > > So, can anyone answer any of the questions below, or do I have to write
> > > > drm for multimedia ?
> > >
> > > The DRM is an architecture for accessing hardware directly.
> > >
> > > What functions are implemented in any given kernel module is driven by
> > > the requirements of the applications running on top of it. That's
> > > typically OpenGL at that point.
> >
> > Daryll, did you read the questions ? I am asking specific things about drm
> > interface. Like what drm handles mean, for example.
> >
> > > So, most of the drivers are not going to have a function call to support
> > > your arbitrary DMA.
> >
> > I am not interested in most drivers. Heck, I am not even looking for that
> > function. I want to know what can I do with the buffer I allocated using
> > drm.
> >
> > Now, I aprreciate your desire to provide some advice, but I am not
> > interested in general considerations of writing a DMA driver. I want to
> > know answers to specific questions, like
> >
> > What "AGP Offset" is used for ?
> >
> > it is not specific to any card, it is not specific to what I am trying to
> > do. Can anyone answer it ?
>
> First, your best bet is to read and understand the 3d driver associated with
> whatever hardware you're looking at. Most of the questions you are asking
> can be most easily answered by examination of the code.
That's what I am trying to do. With not much luck so far. The reason (at
least to me) is that the 3d driver is the interaction of 3 parts: kernel
drm module, XFree driver (like radeon_dri.c) and the dri part (whatever
goes into radeon_dri.so).
>
> Second, it is easiest to answer your questions if you refer to specific lines
> in specific files. There is no variable called "AGP Offset" anywhere in the
> drm. Maybe there are some with similar names, but I can't tell which one
> you're talking about.
>
Finally, someone who knows the stuff :)) No, there is no such variable,
but this phrase I plucked from the comment. Here is an example from
radeon.h:
/* CP vertex/indirect buffer data */
unsigned long bufStart; /* Offset into AGP space */
drmHandle bufHandle; /* Handle from drmAddMap */
drmSize bufMapSize; /* Size of map */
int bufSize; /* Size of buffers (in MB) */
unsigned char *buf; /* Map */
int bufNumBufs; /* Number of buffers */
drmBufMapPtr buffers; /* Buffer map */
Now, from these I guess that *buf is where I can access the data directly
for Xserver. bufSize is the size of the thing - does it have to be in MB ?
Or just page-aligned is fine ? bufStart - what do I use this for ? Can I
use it to reference data in the buffer or do I have to add or subtract a
magic number from it before writing into card's registers ? (and to answer
your questions: I have made a copy of the same fields /with buf replaced
with capture and allocated space.. nothing seems to crash.., 3d workds,
1mb is reserved someplace. /)
> Thirdly, nobody's got the time or patience to explain the entire workings of
> the drm to you. Make an honest attempt to read and understand the code. Ask
> a few questions and you'll get a few answers. Ask a thousand questions and
> you will be lucky to get any at all.
Ok, I'll leave the other questions for later.
Vladimir Dergachev
>
> Keith
>
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