lkml.org 
[lkml]   [2001]   [Jan]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectStrange mm problem??

I'm having a crazy mm problem with the new 2.4.0 kernel. I've got a
device in which I do DMA i/o from user space.

I have a dd which allocs mem (for use as a DMA staging area) and then
I use remap_page_range() to map it into user land (via the mmap()
interface). I was using __get_dma_pages(), the MAP_NR macro, and
mem_map_reserve() to allocate and reserve the mem.

It works great in 2.2.12 and 2.4.0-test4. Now with 2.4.0 production,
I borrowed the uvirt_to_kva(), uvirt_to_bus(), kvirt_to_pa()
and rvmalloc() functions from drivers/media/video/bttv-driver.c

Now here's the wierd part: Memory is allocated ok and I can read to and
write from it in the dd. But in the userland application, I can write
to it OK, but all reads return 0xff!

I'm sure I'm doing something wrong but can't figure out what!

Any assistance would be appreciated.

REgards,

Howard G Page
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:24    [W:0.028 / U:0.932 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site