Nicolas Pitre wrote:

quoted text
> I have implemented highmem for ARM.  To catch wrong usage of __pa() and

>

> One issue is that bootmem.h uses __pa(MAX_DMA_ADDRESS). However

> MAX_DMA_ADDRESS on ARM is defined as 0xffffffff because there is usually

> no restriction on the maximum DMA-able address.

>

> RMK suggested that those places should be using ISA_DMA_THRESHOLD

> instead -- here's an excert of our conversation on this topic:

>

ok so do
#define MAX_DMA_ADDRESS ISA_DMA_THRESHOLD
 >> I suspect all those places which are doing __pa(MAX_DMA_ADDRESS) really

quoted text
>> want to be using ISA_DMA_THRESHOLD - that's something to raise on LKML

>> if it's causing problems.

MAX_DMA_ADDRESS is the highest address used for ZONE_DMA / GFP_DMA
Does ISA_DMA_THRESHOLD have any meaning on ARM? If you use old ISA stuff then

you need CONFIG_ZONE_DMA and therefore also MAX_DMA_ADDRESS.
If not then there is no need to define CONFIG_ZONE_DMA and MAX_DMA_ADDRESS

looses its usual meaning.

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