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SubjectWhat does pci_map_single do
Date
Hi All,

I wanted to use DMA in my device driver.

1. pci_map_single will transfer the data from RAM (kernel area) to the
hardware accessible area and will provide with a pointer which can then be
passed to the hardware.
2. In the above function the "size" parameter indicates the amount of DMA
transfer.
Am I correct in the above two points? If I am wrong please correct me.

In the Linux Device driver book (page 408), he says, data must be explicitly
flushed from the processor cache. And data flushed this way is not avaliable
to the device.

This means that we must flush the processor cache before calling
pci_map_single. How can we achieve this.

Thanking You
Shesha



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