Messages in this thread | | | Date | Tue, 06 Apr 2010 12:44:07 -0700 | From | "H. Peter Anvin" <> | Subject | Re: why choose 896MB to the start point of ZONE_HIGHMEM |
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On 04/06/2010 12:20 PM, Frank Hu wrote: >> >> The ELF ABI specifies that user space has 3 GB available to it. That >> leaves 1 GB for the kernel. The kernel, by default, uses 128 MB for I/O >> mapping, vmalloc, and kmap support, which leaves 896 MB for LOWMEM. >> >> All of these boundaries are configurable; with PAE enabled the user >> space boundary has to be on a 1 GB boundary. >> > > the VM split is also configurable when building the kernel (for 32-bit > processors).
I did say "all these boundaries are configurable". Rather explicitly.
-hpa
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