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Using More Than 1GB of Memory on a Linux Host

By default, Linux kernels in the 2.2.x series support 1GB of physical memory. If you want to use more memory in Linux, you can take one of several approaches.

  • Upgrade to a 2.4.x series kernel that allows for more physical memory.
  • Recompile your kernel as a 2GB kernel using the CONFIG_2GB option.
  • Enable the CONFIG_BIGMEM option to map more physical memory. (This approach requires special steps, described in detail in the Workarounds section below, to work with VMware products.)
  • The CONFIG_2GB option calls for recompiling your kernel as a 2GB kernel. You do this by recompiling your kernel with CONFIG_2GB enabled. This allows Linux to support nearly 2GB of physical memory by dividing the address space into a 2GB user section and a 2GB kernel section (as opposed to the normal division of 3GB for user and 1GB for kernel).

    The third approach uses the CONFIG_BIGMEM option in Linux. With the CONFIG_BIGMEM option enabled, the kernel does not directly address all of physical memory and it can then map 1GB (or 2GB) of physical memory into the address space at a time. This allows the use of all of physical memory at the cost of changing the semantics the kernel uses to map virtual to physical addresses. However, VMware products expect physical memory to be mapped directly in the kernel's address space and thus do not work properly with the CONFIG_BIGMEM option enabled.

    Workarounds

    If you are using a 1GB kernel with CONFIG_BIGMEM enabled and have 960MB to 1983MB of memory, VMware Workstation does not run. To work around this issue, you can either:

  • Recompile the kernel as a 2GB kernel by enabling the CONFIG_2GB option. This allows for 100 percent use of physical memory.
  • Pass the boot-time switch mem=959M at the LILO prompt, or add it to lilo.conf, to disable CONFIG_BIGMEM and thus allow you to run VMware Workstation. To do this:
  • At the LILO prompt, type linux-2.2.16xxx mem=959M.
  • Or, edit lilo.conf. In the kernel section, add this line:
    append mem="959M"
  • If you have a 1GB kernel with CONFIG_BIGMEM enabled and have more than 1983MB of memory, you can do one of the following:

  • Recompile the kernel as a 2GB kernel by enabling the CONFIG_2GB option and either pass the boot-time switch mem=1983M at the LILO prompt or add it to lilo.conf. To use the switch:
  • At the LILO prompt, type linux-2.2.16xxx mem=1983M.
  • Or, edit lilo.conf. In the kernel section, add this line:
    append mem="1983M"
  • Pass the boot-time switch mem=959M at the LILO prompt or add it to lilo.conf to disable CONFIG_BIGMEM. To use the switch:
  • At the LILO prompt, type linux-2.2.16xxx mem=959M.
  • Or, edit lilo.conf. In the kernel section, add this line:
    append mem="959M"
  • If you are using a 2GB kernel with CONFIG_BIGMEM enabled and have 1984MB or more memory, VMware Workstation does not run. You can either pass the boot-time switch mem=1983M at the LILO prompt, or add it to lilo.conf to disable CONFIG_BIGMEM and thus allow you to run VMware Workstation. To use the switch:

  • At the LILO prompt, type linux-2.2.16xxx mem=1983M.
  • Or, edit lilo.conf. In the kernel section, add this line:
    append mem="1983M"
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