Claus-Justus Heine <[EMAIL PROTECTED]> writes: > Michel Dänzer <[EMAIL PROTECTED]> writes: > > > > And one major feature on x86 machines are the iommu facilities of the > > > AGP chipsets. Implementing a fake "AGP" driver for architectures which > > > already have iommu facilities for their PCI subsystems seems to be > > > fairly easy. The user-land drivers of the X-server can (perhaps?) > > > remain unchanged. The drm kernel modules need to be adjusted, of course. > > > > Sounds plausible to me, but I can't tell for sure. > > > > Alternatively, maybe you could leverage the pcigart code of the ATI > > drivers.
Basically, it seems to work now -- in principle. Synchronization with the X-Server is flaky; maybe there is a mb() issue or something like that. The current state is: I have added dummy "AGP" support to agpgart_be.c which uses the PCI IOMMU of the Alpha to map agp memory virtually contigious into the PCI DMA space. Allocation is performed with vmalloc, so that the CPU side also gets a virtually contigous buffer. Using ioremap() on the DMA memory cannot work on the Alpha, you really can only remap "real" PCI memory with that. Then, of course, one needs to disable the AGP mode in the mga dri driver. Seemingly the mga driver used chunks of at most 128kb at the moment. So maybe one could even support PCI mode on x86 systems, provided there are enough 128k chunks available. Allocation could be done with pci_alloc_consistent(). It's a quick hack at the moment, but can be cleaned up. It's a little bit crazy, because the G450 is quite an old card, and it is to be expected that there will be no new generations of Alpha processors anymore, now that Intel has bought the stuff from Compaq. But it is fun anyway. I plan to do a little cleanup and then to address the communication flaws between the DRI modules and the X server. At the moment I'll stick to the dummy AGP interface, as this requires only small changes to the mga DRI kernel module and the DRI MesaGL module (one only needs to disable AGP mode). Greetings Claus -- Claus-Justus Heine [EMAIL PROTECTED] http://www.instmath.rwth-aachen.de/~heine/ Ftape - the Linux Floppy Tape Project Home Page : http://www.instmath.rwth-aachen.de/~heine/ftape/ _______________________________________________ Dri-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/dri-devel
