Socket buffer allocation outside DMA-able memory

[art <art@sigrand.ru>]

Hello all!
I work with ADM5120 chip. it has embedded switch.
Switch descriptor has 25-bit dma addres field - so addressible only
32Mb!
My system has 64Mb memory. But I have to set 32Mb to make it work!
I thought that setting DMA mask can help. So in
/arch/mips/adm5120/setup.c i make:

static struct platform_device adm5120hcd_device = {
        .name           = "adm5120-hcd",
        .id             = -1,
        .dev            = {
        .dma_mask               = &hcd_dmamask,
        .coherent_dma_mask      = 0x01ffffff,
        },
        .num_resources  = ARRAY_SIZE(adm5120_hcd_resources),
        .resource       = adm5120_hcd_resources,
};
But It is wrong, because dev_alloc_skb dont know to which device it
allocates buffer!

How to tell kernel allocate skbuffers in less then 32Mb addrspace whet
system has 64Mb?

-- 
Best regards,
 art                          mailto:art@sigrand.ru