Platform-specific limits

Limit x86 PPC MIPS SH-4 ARMv4 ARMv6 ARMv7
System RAM 64 GB 64 GB 1 TB 512 MBa 4 GB 4 GBb 4 GB
Physical addressing 36-bit 36-bit 40-bit 32-bit 32-bit 32-bit 32-bit
CPUsc 32d 32 32 2 1 1 4
Virtual address spacee 3.5 GB 3 GB 2 GB 2 GB 32 MB 2 GB 2 GB

a 32-bit addressing gives 4 GB of space, but not all can be used for system RAM on some platforms. Some space is reserved for devices, and some platforms might impose other restrictions.

b The actual amount of RAM is determined by the system-on-chip implementation.

c The hardware might further limit the number of CPUs.

d If you plan to use more than 8 CPUs on an x86 platform, you must use the 6.5 or later version of procnto-smp with startup-bios or startup-apic.

e These are the absolute maximum limits for the virtual address space; you can reduce them by setting the RLIMIT_AS resource with setrlimit().