Accessing more physical memory

• Only less than 1GB memory address-able directly through kernel virtual address space

• If more physical memory is present on the platform:

• Part of the memory will not be access-able by kernel space, but can be used by user-space
• To allow kernel to access to more physical memory:
• Change 1GB/3GB memory split (2GB/2GB) ? => but reduces total memory available for each process
• Change for a 64bits architecture ;-)
• Activate the 'highmem' support if available for your architecture:
• Allows kernel to map parts of its non-directly access-able memory
• Mapping must be requested explicitly
• Limited addresses ranges reserved for this usage