I want to create some memory to use for DMA transfers. (Using Linux 2.6.18-128.el5 #1 SMP)
I have a API stack+kernel driver for my H/W that can do this for me, but its very very slow!
If I use the API to create a DMA transfer, it allocates some memory very high up in System RAM (eg 0x7373a6f8 on one run). (I have the ICD of the device, so have a memory map mmap'd over, this is how I can find this address out, and how in the end I want to SET to my own address, and hence the /dev/mem in the maps below)
I cannot seem to be able to mmap memory around this high address, presumably as its out of my virtual memory space and im being blocked by the kernel?
What I want to be able to do is either use (map) this address given, so I can read/write to it, OR create my own physical memory that I can read/write to.
# cat /proc/iomem
00000000-0009fbff : System RAM
00000000-00000000 : Crash kernel
000a0000-000bffff : Video RAM area
000c0000-000c7fff : Video ROM
000f0000-000fffff : System ROM
00100000-7fd64fff : System RAM # Is this all of /dev/mem?
00400000-00612916 : Kernel code
00612917-006ef9db : Kernel data
# cat /proc/3450/maps
08207000-08228000 rw-p 08207000 00:00 0 [heap]
b7e7b000-b7f85000 rw-p b7e7b000 00:00 0
b7f89000-b7f8a000 rw-p b7f89000 00:00 0
b7f8a000-b7f8b000 rw-s 80114000 00:11 1541 /dev/mem
b7f8b000-b7f8d000 rw-p b7f8b000 00:00 0
bff70000-bff85000 rw-p bffea000 00:00 0 [stack]