Messages in this thread | | | Date | Sat, 24 Mar 2007 00:41:00 +0530 | From | "Ameya Mitragotri" <> | Subject | in-kernel data transfer between devices |
| |
Hello, I'm trying to write data from device memory (VRAM in this case) to the HDD with a kernel module. I want to avoid using the cache so i tried to do a direct-io. Reading the code i figured it used 'get_user_pages' and since VRAM is io mapped, those pages are marked VM_IO and hence directio fails. Why is it taboo to write VM_IO pages using directio? (is it because Device -> Device DMA is not possible?)
Now attempting to still do the same, im trying to copy VRAM data to a buffer and still try and use the directio path. it will mean bypassing the get_user_pages and may mean ugly hacking, but then i also read a little about splice. Wondering if splice is the way to go for a device memory to disk in kernel data transfer?
I'm doing the above as an experiment. My actual goal is to transfer data between devices in-kernel.
Thanks Ameya - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |