Re: DMA bitblt pageing?
On Gwe, 2005-07-08 at 09:18, Thomas Hellström wrote: Is this because they are not physically contigous or because they may not be accessible to the PCI device? I was thinking of using vmalloced memory instead of kmalloced for the device sg-list, and since it is a linked list it should be able to deal with non-contigous pages. It may not be physically accessible. The dma allocation functions should be used to reliably allocate DMA spaces. Preferrably I'd like to have an implementation where one can start a DMA bitblt operation then return to whatever is being done at the moment, and a sync function called to make sure the DMA has finished. This will require, however, a small sg-list / page pointer array ring buffer and that all free() and unlock operations can be done from the DMA complete interrupt handler. This is near enough how video4linux works except that it uses a ring buffer rather than keep freeing (as its TV capture) so only does the pci write to stop, read to avoid posting and free at close time. Alan --- This SF.Net email is sponsored by the 'Do More With Dual!' webinar happening July 14 at 8am PDT/11am EDT. We invite you to explore the latest in dual core and dual graphics technology at this free one hour event hosted by HP, AMD, and NVIDIA. To register visit http://www.hp.com/go/dualwebinar -- ___ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
Re: DMA bitblt pageing?
Hi! 3.) Is memory allocated with vmalloc always locked into physical memory until freed? Yes but it may not be DMAable. Thanks. Is this because they are not physically contigous or because they may not be accessible to the PCI device? I was thinking of using vmalloced memory instead of kmalloced for the device sg-list, and since it is a linked list it should be able to deal with non-contigous pages. Preferrably I'd like to have an implementation where one can start a DMA bitblt operation then return to whatever is being done at the moment, and a sync function called to make sure the DMA has finished. This will require, however, a small sg-list / page pointer array ring buffer and that all free() and unlock operations can be done from the DMA complete interrupt handler. Maybe a bit over-complicated but very useful for XvMC subpictures and speculative OpenGL texture downloads to system memory. /Thomas --- This SF.Net email is sponsored by the 'Do More With Dual!' webinar happening July 14 at 8am PDT/11am EDT. We invite you to explore the latest in dual core and dual graphics technology at this free one hour event hosted by HP, AMD, and NVIDIA. To register visit http://www.hp.com/go/dualwebinar -- ___ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
DMA bitblt pageing?
Hi! I'm trying to incorporate a patch I got for DMA bitblt into the via drm. Probably useful for a lot of things including Xv image transfer, Texture downloads and Exa acceleration. Got it working, but to really know what I'm doing, being a kernel programming novice, could I have some help with these ones? 1.) get_user_pages() should presumably lock a page into physical memory. Will this always cause a segfault for an invalid address? 2.) Unlocking pages previously locked with get_user_pages(): is page_cache_release() sufficient or are more calls needed? Could the unlocking functions be called from an interrupt handler? Is a refcount maintained for this page locking or is it one-level only? 3.) Is memory allocated with vmalloc always locked into physical memory until freed? 4.) Are there any DRM macros for the above, to make porting to other OS'es easier? Thanks for any advice, Thomas Hellström --- This SF.Net email is sponsored by the 'Do More With Dual!' webinar happening July 14 at 8am PDT/11am EDT. We invite you to explore the latest in dual core and dual graphics technology at this free one hour event hosted by HP, AMD, and NVIDIA. To register visit http://www.hp.com/go/dualwebinar -- ___ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
Re: DMA bitblt pageing?
http://lwn.net/Kernel/LDD3/ Chapter 15 explains how DMA works under Linux. -- Jon Smirl [EMAIL PROTECTED] --- This SF.Net email is sponsored by the 'Do More With Dual!' webinar happening July 14 at 8am PDT/11am EDT. We invite you to explore the latest in dual core and dual graphics technology at this free one hour event hosted by HP, AMD, and NVIDIA. To register visit http://www.hp.com/go/dualwebinar -- ___ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
Re: DMA bitblt pageing?
Jon Smirl wrote: http://lwn.net/Kernel/LDD3/ Chapter 15 explains how DMA works under Linux. Thanks! /Thomas --- This SF.Net email is sponsored by the 'Do More With Dual!' webinar happening July 14 at 8am PDT/11am EDT. We invite you to explore the latest in dual core and dual graphics technology at this free one hour event hosted by HP, AMD, and NVIDIA. To register visit http://www.hp.com/go/dualwebinar -- ___ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
Re: DMA bitblt pageing?
On Iau, 2005-07-07 at 23:50, Thomas Hellström wrote: 1.) get_user_pages() should presumably lock a page into physical memory. Will this always cause a segfault for an invalid address? You'll get an error for invalid space. You may also get null entries in the array for locking the paged if they relate to a hole in memory. 2.) Unlocking pages previously locked with get_user_pages(): is page_cache_release() sufficient or are more calls needed? Could the unlocking functions be called from an interrupt handler? Is a refcount maintained for this page locking or is it one-level only? It is refcounted. 3.) Is memory allocated with vmalloc always locked into physical memory until freed? Yes but it may not be DMAable. --- This SF.Net email is sponsored by the 'Do More With Dual!' webinar happening July 14 at 8am PDT/11am EDT. We invite you to explore the latest in dual core and dual graphics technology at this free one hour event hosted by HP, AMD, and NVIDIA. To register visit http://www.hp.com/go/dualwebinar -- ___ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
