Hi, Am Montag, den 17.05.2010, 22:14 +0200 schrieb Primoz PETERLIN: > 2010/5/17 Klaus Stengel <klaus.sten...@asamnet.de>: > > Bernhard Praschinger wrote: > >> I'd really like to hear of a success story (or how you call it). That a > >> zoran card works on a 64 bit machine with a 64bit kernel. > > > > I have a DC10+ running with a 64-bit Linux 2.6.26 on Intel Core2 > > Machine. But I had to do some modifications to the driver because the > > Zoran card can only adress the lower 32-bit of RAM with its DMA engine > > so the buffers for data transfer need to be allocated in that area. I > > did post the necessary changes for some older Kernel versions two years > > ago on the developer list, but I didn't receive much feedback iirc. > > Now that's interesting. Could it be that it worked for me because I > didn't have more than 4 GB of memory? (Yes, I know, you may ask why > would one bother at all with a 64-bit system in that case).
Well, it's certainly related. The more memory you have, the bigger are the odds that the buffers will be allocated outside the 4 GB that can be addressed with 32 bits. But even if you don't have more than 4 GB of RAM, most Mainboards start to map parts of the available memory into the bigger address space much earlier. You can check this if you run the command: cat /proc/iomem | grep 'System RAM' The output should look something like this: 00000000-0009ebff : System RAM 00100000-bd4a0fff : System RAM bd4a7000-bd5b6fff : System RAM bd60f000-bd6c5fff : System RAM bd9ff000-bd9fffff : System RAM 100000000-13bffffff : System RAM If there are (hex-)numbers which have more than 8 digits, you definitely have some memory areas that require 64-bits to be accessed. For the machine from the example above, everything above 3033 MB (=bd9fffff hex) was remapped beyond the 4 GB limit. It might be possible that your machine already does this sort of remapping and if parts of the data buffers happen to be allocated in one of those remapped areas, the driver will fail. That's also the reason why passing mem=4G as kernel parameter most certainly won't help, but limiting the used memory to 2 GB should be safe for most boards. Regards, Klaus. ------------------------------------------------------------------------------ _______________________________________________ Mjpeg-users mailing list Mjpeg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mjpeg-users
