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User space to PCI Memory
Name: basu_arani Date: May 2, 2004 at 01:31:23 Pacific OS: Linux CPU/Ram: Pentium3/256
Comment:
Hi There,
I am developing a driver for a communication card in linux. The working of the driver is as follows:
The data has to be transferred from user space memory to some memory on a particular PCI card. This card is having the PLX PCI 9054 with a DMA controller.
If I have to pass the data from the user program to the PCI Memory, the data has to be first passed from user space to the kernel space and then from there to the PCI Memory. This is resulting in a lot of bandwidth wastage.
Is it possible for a kernel module to access the user space memory directly, so that I can transfer the data directly from the userspace to the PCI memory.
Name: Wolfbone Date: May 2, 2004 at 10:02:37 Pacific
Reply:
Do you mean something like mmio as used by ALSA and eg. the /usr/src/linux/drivers/net/8139too.c driver? I've only had experience of mmap (info Libc, /usr/include/sys/mman.h) from the user side so I couldn't tell you how to write the driver-side mapping but there are plenty of examples in the kernel source.
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