On Sat, Feb 28, 2015 at 10:24:16AM +0330, Navid Movahedi wrote:
Hi I'm reading the seabios source code, the usb part and found that for example in usb-uhci.c file, in some parts malloc_low is used and in other malloc_high Now, the question: is it important for usb endpoints or pipes to be allocated in low or high zone of memory? and if yes, why?
There is some documentation on the memory zones at: http://www.seabios.org/Memory_Model
In the uhci driver, the low memory zone is used for any allocations that need to be read/writable to code that runs in 16bit mode (uhci_send_pipe and uhci_poll_intr). The high memory allocations are for DMA structures that aren't read/written to by the CPU during runtime.