As I understand it, in a Linux / i686 system, there are three zones: DMA
(0 - 2^24-1), low (2^24 - 2^30-1) and high (2^30 and up). And the hardware
(PAE) apparently distinguishes memory addresses above 2^32-1 as well.
Questions:
1. Shouldn't there be *four* zones: (DMA, low, high and PAE)?
2. Isn't the boundary at 2^30 really irrelevant and the three "correct"
zones are (0 - 2^24-1), (2^24 - 2^32-1) and (2^32 - 2^36-1)?
3. On a system without ISA DMA devices, can DMA and low be merged into a
single zone?
4. It's pretty obvious exactly which functions require memory under 2^24 --
ISA DMA. But exactly which functions require memory under 2^30 and which
functions require memory under 2^32? It seems relatively easy to write a
Perl script to truck through the kernel source and figure this out; has
anyone done it? It would seem to me a valuable piece of information -- what
the demands are for the relatively precious areas of memory under 1 GB and
under 4 GB.
-- M. Edward Boraskyznmeb@borasky-research.net http://www.borasky-research.net
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/