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Platform Notes: SPARCstation 10SX and SPARCstation 20 System Configuration Guide

Configuring SXDRAM

This section lists the steps to follow in order to configure SXDRAM. It also discusses the constraints imposed by the system software and hardware. It is essential that you understand the system memory map before you configure SXDRAM.

Note that there are some key differences in the way memory is arranged on the SPARCstation 10SX and the SPARCstation 20:

Information specific to the SPARCstation 20 is provided in "Memory Bank Layout on the SPARCstation 20". To plan SXDRAM configurations for those systems, take this information into account when applying the principles explained in the material covering the SPARCstation 10SX.

Memory Bank Layout on the SPARCstation 10SX

There are two memory banks on a SPARCstation 10SX. Bank 0 is comprised of slots 0, 1, 2, and 3. Bank 1 is comprised of slots 4, 5, 6, and 7. These 8 slots are available for configuring memory on the SPARCstation 10SX. Each bank of memory can map 256 MByte of physical address space. Each slot in each memory bank maps 64 MByte of physical address space.

The beginning physical address for bank 0 is 0. For bank 1, it is 0x10000000.

Slots 4 must be configured with a VSIMM; slot 5 may be configured with either a DSIMM or a VSIMM (CG14). The SPARCstation 10SX supports 16 MByte and 64 MByte DSIMMs, and 4 MByte and 8 MByte VSIMMs. Each slot maps 64 MByte of physical address space regardless of the size and type of SIMM that is configured in the slot.

Figure 2-1 Memory Layout on Mother Board of SPARCstation 10SX

Graphic

The table below illustrates the physical address map of a system configured with 16 MByte DSIMMS in all the slots

Table 2-1 SPARCstation 10SX System Memory Layout 16 MByte DSIMMs only
 SIMM Slots DSIMM Size Physical Address
 Slot 7 16 MByte DSIMM 0x1c000000
 Slot 3 16 MByte DSIMM 0xc000000
 Slot 6 16 MByte DSIMM 0x18000000
 Slot 2 16 MByte DSIMM 0x8000000
 Slot 5 16 MByte DSIMM 0x14000000
 Slot 1 16 MByte DSIMM 0x4000000
 Slot 4 16 MByte DSIMM 0x10000000
 Slot 0 16 MByte DSIMM 0x0

Table 2-2 below illustrates the physical address map of a system configured with one 4 MByte VSIMM installed in slot 4 and 16 MByte DSIMMs in the remaining slots.

Table 2-2 SPARCstation 10SX System Memory Layout One 4 MByte VSIMM, Seven 16 MByte DSIMMs
 SIMM Slots DSIMM/VSIMM Size Physical Address
 Slot 7 16 MByte DSIMM 0x1c000000
 Slot 3 16 MByte DSIMM 0xc000000
 Slot 6 16 MByte DSIMM 0x18000000
 Slot 2 16 MByte DSIMM 0x8000000
 Slot 5 16 MByte DSIMM 0x14000000
 Slot 1 16 MByte DSIMM 0x4000000
 Slot 4 4 MByte VSIMM 0xf0000000
 Slot 0 16 MByte DSIMM 0x0

Thus, on systems configured with 16 MByte DSIMMS, the maximum size of a physically contiguous block of DRAM is 16 MByte. However, you can reserve multiple blocks of SXDRAM on such systems. In order to be able to configure a single block of SXDRAM greater than 16 MByte, the system must be configured with 64 MByte DSIMMs.

Table 2-3 illustrates a system configured with one 4 MByte VSIMM and seven 64 MByte DSIMMs.

Table 2-3 SPARCstation 10SX System Memory Layout One 4 MByte VSIMM, Seven 64 MByte DSIMMs
 SIMM Slots DSIMM/VSIMM Size Physical Address
 Slot 7 64 MByte DSIMM 0x1c000000
 Slot 3 64 MByte DSIMM 0xc000000
 Slot 6 64 MByte DSIMM 0x18000000
 Slot 2 64 MByte DSIMM 0x8000000
 Slot 5 64 MByte DSIMM 0x14000000
 Slot 1 64 MByte DSIMM 0x4000000
 Slot 4 4 MByte VSIMM 0xf0000000
 Slot 0 64 MByte DSIMM 0x0

This layout results in one contiguous block of 256 MBytes (slots 0, 1, 2, and 3) beginning at physical address 0, and another block of 192 MBytes (slots 4, 5, 6, and 7) beginning at physical address 0x14000000. Therefore, the maximum amount of DRAM that can be installed in this configuration is 448 MBytes.

A typical system will most likely have 16 MByte and 64 MByte DSIMMs, and VSIMMs. There are a large number of possible permutations of the system configuration which, due to space limitations, will not be discussed here.

To be able to allocate the largest possible block of SXDRAM with a given set of VSIMMs and DSIMMs, use the illustrations in this section as a guide.

The next section provides some information unique to the SPARCstation 20. The two sections following that discuss system software constraints and configuration recommendations that involve both systems.

Memory Bank Layout on the SPARCstation 20

On the SPARCstation 20, the physical sequence of slots is different from that slots on the SPARCstation 10SX. The slots that can be used for VSIMMs differ as well. The different layouts are compared in Table 2-4.

Table 2-4 Comparing Slot Locations on the SPARCstation 10SX and SPARCstation 20
 Slot Names on SPARCstation 10SX Slot Names on SPARCstation 20
 Slot 7 Slot 0
 Slot 3 Slot 2
 Slot 6 Slot 5
 Slot 2 Slot 3
 Slot 5 (can be VSIMM 1) Slot 6
 Slot 1 Slot 1
 Slot 4 (can be VSIMM 0) Slot 7 (can be VSIMM 0)
 Slot 0 Slot 4 (can be VSIMM 1)

System Software Constraints for SXDRAM Configuration

The following constraints are described in terms of the SPARCstation 10SX, but the same concerns apply to the SPARCstation 20.

  1. The first slot (slot 0) must always be configured with a DSIMM.

  2. The minimum recommended amount of memory required for reasonable SPARCstation 10SX performance is 32 MByte. Thus, to be able to reserve SXDRAM, a system should be configured with more than 32 MBytes of DRAM. However, users can configure the minimum amount of memory that must be reserved for system use by using the -l option of the sxconfig (1M) command. The difference between the amount of DRAM installed on the system and the configured minimum limit (32 MBytes by default) is the maximum amount of memory that can be reserved for SXDRAM.

  3. The amount of physically contiguous memory that should be reserved must be specified as an integer multiple of 1 MByte. Thus, the minimum amount that can be reserved is 1 MByte.

Recommended DSIMM/VSIMM Configuration for the SPARCstation 10SX

  1. The VSIMM can only be installed in slots 4 or 5 on the SPARCstation 10SX. If there is only one VSIMM, it can be installed in either slot 4 or 5. To install the VSIMM in slot 5, an AVB (Auxiliary Video Board) card is required. This card is not bundled with the SPARCstation 10SX.

  2. Always install a 16 MByte DSIMM in slot 0 when you have a combination of 16 MByte and 64 MByte DSIMMs.

  3. If the memory system consists only of 16 MByte DSIMMs. They can be configured in any slots, provided that the first 16 MByte DSIMM is installed in slot 0.

  4. Within a memory bank, always install the DSIMMs in the order of decreasing DSIMM sizes (the ordering does not matter if all the DSIMMs are of the same size). In other words, if there is a combination of 64 MByte DSIMMs and 16 MByte DSIMMs, install the 64 MByte DSIMM in the lowest-number slot, followed by the 16 MByte in the immediate next slot.

When configuring the memory subsystem with 64 MByte DSIMMs and 16 MByte DSIMMs, the following examples can be used as a guide:

System configuration: 1 VSIMM, 2 16 MByte DSIMMs, 2 64 MByte DSIMMs.

This an be configured as:

or be configured as:

SXDRAM Configuration

The operating system includes a driver for reserving and managing physically contiguous memory. The memory should be reserved as part of the boot process, because it is likely to be the least fragmented at this time, and chances of finding large blocks of physically contiguous memory are higher during boot time.

The amount of SXDRAM to reserve can be specified by using the sxconfig(1M) command. sxconfig can be executed only by a process with superuser privileges. Here are some examples of sxconfig command use.

To disable fragmentation, enter:

# sxconfig -n

To restore all configuration parameters to the default values, enter:

# sxconfig -d

By default, 0 MBytes of physically contiguous memory is reserved, fragmentation is not allowed, and 32 MBytes of memory is reserved for system use.

To display the current configuration parameters in the driver configuration file, enter:

# sxconfig -c

If the system was not booted after the last time the configuration parameters were changed, then the displayed values will not reflect the actual system set-up. For more information about using sxconfig, refer to the on-line man page.

The sxconfig command resides in the directory /platform/SUNW,SPARCstation-10,SX/sbin; the shell environment variable PATH must include this directory. To find out whether the PATH environment variable includes the /platform/SUNW,SPARCstation-10,SX/sbin directory, type

# echo $PATH

:

Your search path will be displayed. An example:

 /bin:/etc/:/usr/bin:

If the line displayed does not include /platform/SUNW,SPARCstation-10,SX/sbin, enter the following if you are in either the Bourne shell or the Korn shell:

# PATH=$PATH:/platform/SUNW,SPARCstation-10,SX/sbin export PATH

followed by:

# export PATH

if you are in the Bourne shell.

If you are in the C shell, enter:

# setenv PATH "$PATH /platform/SUNW,SPARCstation-10,SX/sbin"

If 16 MBytes of memory must be reserved, enter:

# sxconfig -s 16

On a system configured with 16 MByte DSIMMs, the maximum amount of SXDRAM that can be reserved in a single block is 16 MBytes. On such systems, when more than 16 MBytes of memory must be reserved for SXDRAM, the sxconfig command can be used to specify that fragmented reservation of the requested amount of SXDRAM is allowed. For example, to reserve 32 MBytes of memory on a system configured with 16 MBytes, enter:

# sxconfig -s 32 -f

sxconfig and reboot causes a search of the system page pool for a contiguous block of memory of the specified size. If the block of memory is found, it is reserved. If fragmentation is specified (as shown above), more than 16 MBytes is specified, and the search fails, the operating system searches for contiguous blocks of 16 MBytes. If no blocks of this size are found, the operating system searches for contiguous blocks of 256 KBytes.

When the SXDRAM configuration is finished, halt the system:

# halt

The Open Boot PROM prompt is displayed on the console:

 ok

Boot the system by entering:

ok boot disk -rv

The -r option specifies a reconfiguration boot. The -v option specifies verbose mode. As part of the boot process, the requested amount of SXDRAM will be reserved. Refer to Appendix A, Boot Messages for a listing of the messages that will be displayed.

After the system is rebooted, log in, start OpenWindows, and start the XGL application of your choice.