Hello,
I am porting a FEC driver from linux 2.6.10 to uclinux which requires
the usage of DMA transfers to function.
In the FEC driver, I need to allocate a DMA buffer using a call like
"kmalloc(sz, GFP_DMA)". In the stock uclinux kernel, this call fails
because apparently the ZONE_DMA is not defined.
In order for me to get this FEC driver working, what I need to do (I
think) is the following:
1) define a ZONE_DMA area of 1MB
2) mark the ZONE_DMA region as cache-inhibited
I cannot figure out how to mod the uclinux kernel to make step #1 work
as all my calls to "kmalloc(sz,GFP_DMA)" return NULL. Can someone give
me ideas on how to setup a ZONE_DMA for a coldfire arch? Is there an
alternate way to alloc a buffer which is cache inhibited?
Any help would be appreciated,
Thanks,
Dave Meador
Here is my attempt to mod arch/m68knommu/mm/init.c to enable a ZONE_DMA
zone:
{
unsigned long zones_size[MAX_NR_ZONES] = {0, };
unsigned int dma_reserve = (1*1024*1024); // reserve 1MB for DMA
set_dma_reserve(dma_reserve >> PAGE_SHIFT);
end_mem &= PAGE_MASK;
zones_size[ZONE_DMA] = dma_reserve >> PAGE_SHIFT;
zones_size[ZONE_NORMAL] = ((end_mem - PAGE_OFFSET ) >> PAGE_SHIFT) -
zones_size[ZONE_DMA];
#ifdef CONFIG_HIGHMEM
zones_size[ZONE_HIGHMEM] = 0;
#endif
free_area_init(zones_size);
}
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