Physical Address Extension (PAE) Mode

With the release of Pentium Pro, Intel introduced a mode called PAE (physical address extension) on its advanced processors. By using PAE, Solaris Intel Platform Edition can address up to 32 Gbytes of physical memory. Individual processes are still limited to a maximum of 3.5 Gbytes of virtual address space.

PAE mode enables you to run multiple instances of databases and memory-intensive applications, and to support large numbers of online users on your machine.

It is best to use PCI disk controllers that support dual address cycle (DAC) in your machine because they can transfer data to and from any physical location. Other cards are limited to 4 Gbytes of physical memory; as a result, performance might slow down because the system needs to copy additional memory to transfer data.

Some device drivers are not yet able to take advantage of PAE mode. PCI device drivers written by Sun have been tested on IA machines with more than 4 Gbytes of memory. Its OEM partners intend to test their machines with devices they supply on IA machines with more than 4 Gbytes of memory. In some cases, however, if you add a third-party device driver to your system, it might become unstable, and panics and data corruption might result. If your system becomes unstable and you need that driver, you must disable PAE mode.

Disabling PAE Mode

To disable support for PAE mode, follow these steps:

1. Reboot your machine.

2. Interrupt autoboot by pressing the Escape key.

   The Solaris Device Configuration Assistant starts.

3. Press F2_Continue until the Boot Solaris screen is displayed.

4. Press F4_Boot Tasks.

   The Boot Tasks screen is displayed.

5. Select View/Edit Property Settings.

   The View/Edit Property Settings screen is displayed.

6. Press F4_Create.

   The Create Property screen is displayed.

7. In the Specify Property Name field, type mmu-modlist and press Enter.

8. In the Specify Value field, type mmu32 and press Enter.

   The message "Updating Saved Configuration information..." is displayed on the Updating screen. When the property and value are saved successfully, the View/Edit Property Settings screen is displayed.

9. Press F2_Back.

   The Boot Tasks screen is displayed.

10. Press F3_Back.

    After drivers on your machine are loaded, the Boot Solaris screen is displayed.

11. Continue booting your machine as you normally would.