Messages in this thread | | | From | Roland Dreier <> | Date | Wed, 22 Sep 2004 11:51:34 -0700 | Subject | Re: 1GB/2GB/3GB User Space Splitting Patch 2.6.8.1 (PSEUDO SPAM) |
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Timothy> My question is: Why can't we just shrink the kernel Timothy> address space by that same amount, allowing the kernel Timothy> address space plus the extra to fit into 1GB?
If you have 1 GB of memory and want to map it all into the kernel's address space and the kernel has only 1 GB of address space total, then there is no room for anything else (such as address space to ioremap memory-mapped peripherals or space for vmalloc allocations). Therefore, if you want to have 1 GB of RAM mapped linearly into the kernel's address space, you need strictly more than 1 GB of kernel address space. In practice, 1.25 GB of kernel address space (a PAGE_OFFSET value of 0xb0000000) works well with 1 GB of RAM. That's what I run on my main desktop machine with 1 GB of RAM to avoid HIGHMEM.
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