Messages in this thread | | | Date | Tue, 03 May 2011 17:20:10 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [patch v3] x86: allow ZONE_DMA to be configurable |
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On 05/03/2011 05:00 PM, David Rientjes wrote: > On Wed, 27 Apr 2011, David Rientjes wrote: > >> ZONE_DMA is unnecessary for a large number of machines that do not >> require addressing in the lower 16MB of memory because they do not use >> devices with 16-bit address registers (plus one page byte register). >> >> This patch allows users to disable ZONE_DMA for x86 if they know they >> will not be using such devices with their kernel. >> >> This prevents the VM from unnecessarily reserving a ratio of memory >> (defaulting to 1/256th of system capacity) with lowmem_reserve_ratio >> for such allocations when it will never be used. >> >> Signed-off-by: David Rientjes <rientjes@google.com> > > Peter, is this ready for merge?
+ DMA memory allocation support allows devices with 16-bit address + registers to allocate memory within the first 16MB of address space. + Disable if no such devices will be used.
This is still not correct... this is for devices with less than a 32-bit mask, not just for things that have 24-bit (not 16-bit!) DMA address restrictions.
Please get this right.
Other than that, I don't have any technical objections.
-hpa
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