Command Input ENV [;[D]]
Description
The ENV command allows you to view and configure all PPCBug operational parameters that are kept in Non-Volatile RAM (NVRAM).
The operational parameters are saved in NVRAM and used whenever power is lost. (The NVRAM is also known as the Battery Backed Up RAM.)
Any time PPCBug uses a parameter from NVRAM, the NVRAM contents are first tested by checksum to insure the integrity of the NVRAM contents. In the instance of NVRAM checksum failure, certain default values are assumed.
The debugger operational parameters (which are kept in NVRAM) are not initialized automatically on power-up/warm reset. It is up to you to invoke the ENV command. Once the ENV command is invoked and executed without error, debugger default and/or user parameters are loaded into NVRAM along with checksum data. If any of the operational parameters have been modified, these new parameters will not be in effect until a reset or power-up condition.
If the ENV command is invoked with the D option, ROM defaults will be loaded into NVRAM. If the ENV command is invoked without the D option, you are prompted to configure all operational parameters. You may change the displayed value by typing a new value, followed by the Return key. To leave the field unaltered, press the Return key without typing a new value.
Refer to the board installation and use manual for the location and contents of the board information block, and the size and logical offset of each element.
Note Not all ENV parameters are shown in this manual.
Debugger Commands
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You may also enter a special character, either at the prompt or after typing new data, forscrolling through the fields. The special characters are:
Programming The VMEbus Slave Image Map Decoders.
The VMEbus slave image map decoders allow a VMEbus master to access the resources on the local primary PCI bus, and control the type of access to those resources. These decoders are located in the Universe VMEbus interface chip. The following general procedure can be used with the ENV command to configure the VMEbus slave image map decoders. This is not the only procedure that can be used to program the map decoders. More complete information on this subject can be found in the User’s Manual for the Universe chip, the VMEbus specification, the PCI bus specification, and the Programmer’s Guide for the specific board being used.
1. Determine the desired VMEbus base address. This is the starting, or lowest, address that any resource on the local PCI bus can be accessed on the VMEbus. This address must not allow an overlap of the Universe’s control and status registers or any other VMEbus resource’s address space. The first VMEbus slave decoder (for VME slave image 0) has a 4K-byte resolution but VMEbus slave images 1, 2, and 3, have a 64K-byte resolution.
V or v Go to the next field. This is the default, and remains in effect until changed by entering one of the other special characters.
^ Back up to the previous field. This remains in effect until changed by entering one of the other special characters.
= Re-open the same field
. Terminate the ENV command, and return control to the debugger
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4. Determine the necessary VMEbus slave image control. The value used for slave image control is made up of several bit fields which specify how reads and writes will be processed by the Universe device. The desired value can be determined by progressively ORing together the selected bit fields described below.
To select the type of PCI address space that will respond in the defined VMEbus window, use the following:
0x00000000 for PCI Memory space, zero no bits are set.
0x00000001 for PCI I/O space.
0x00000002 for PCI Configuration space.
To lock PCI transactions resulting from VMEbus Read-Modify-Writes, OR the following value with that chosen above:
0x00000040
To enable 64-bit PCI transactions, OR the following value with those chosen above: 0x00000080
To select the VMEbus address space accesses to decode, OR the value defined here with those chosen above:
0x00000000 for A16 space, zero no bits are set.
0x00010000 for A24 space.
0x00020000 for A32 space.
To select the mode of VMEbus accesses to decode, OR the value defined here with those chosen above:
0x00100000 for non-privileged.
0x00200000 for supervisor.
0x00300000 for both non-privileged and supervisor, two bits set.
To select the type of VMEbus accesses to decode, OR the value defined here with those chosen above:
0x00400000 for data.
0x00800000 for program.
0x00C00000 for both data and program, two bits are set.
To enable prefetch reads for incoming VMEbus block read cycles, OR the following value with those chosen above:
0x20000000
To enable posted writes of incoming data on the VMEbus, OR the following value with those chosen above: 0x40000000
Debugger Commands
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To enable the selected VME Slave Image Map Decoder, OR the following value with those chosen above: 0x80000000
As an example, a control value of: 0xE0F20000
decodes A32, non-privileged and supervisor, data and program VMEbus space, with prefetch reads, and posted writes enabled.
It is the user’s responsibility to ensure that the selected control bits are not destructive, and that the resources present on the VMEbus and PCI bus support the access and transaction controls chosen.
ENV Command Parameters
The parameters that can be configured with ENV are listed and described in your board-specific installation and use manual.
Systems with Wide SCSI Drives Running AIX
If AIX (or some other OS) is booted on a system with wide SCSI drives, and then the system is reset, PPCBug will not be able to access the wide SCSI drives. This problem may be corrected by running ENV and enabling PPCBug to reset the SCSI bus on startup as follows:
Local SCSI Bus Reset on Debugger Startup [Y/N] = N? y
This ENV change should be made to all PowerPlus architecture systems running AIX.
Note This problem is fixed in PPCBug release 3.2 and later.
LED/Serial Startup Diagnostic Codes
These codes can be displayed at key points in the initialization of the hardware devices. Should the debugger fail to come up to a prompt, the last
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Serial Startup Code LF Enable [Y/N]=N?
The list of LED/serial codes is included in the section on MPU, Hardware, and Firmware Initialization in Chapter 1.
Memory Usage Control
The amount of RAM that PPCBug uses may be contained with an NVRAM parameter. This parameter is set by the ENV line:
Maximum Memory Usage (Mb, 0=AUTO) = 1?
If the parameter is set to a non-zero value, it is interpreted as the maximum number of megabytes that PPCBug is allowed to control. At start-up, one megabyte at the top of physical memory is set aside. If more than this is required, allocation is expanded toward smaller addresses unless the specified maximum value is achieved. If this occurs, the current memory request will be denied followed, most likely, by failure of the current activity.
If the parameter is set to zero, expansion is unlimited.
In no case, however, is expansion allowed to exceed one-half of the available memory regardless of how high the parameter is set.
Two things should be considered in setting this parameter:
1. Memory, once acquired, is never returned. The total memory used sets the system’s maximum use level. This number may be obtained using the Memory Manager Query command (MMGR).
2. Expansion is incremental and on demand. Only what is actually required will be used.
Thus, the total used is the system’s current maximum usage level gauge.
This number may be obtained, after the system has exercised, using the Memory Manager Query command (MMGR).
Debugger Commands