AST RESEARCH, INC. INFORMATIONAL BULLETIN # 0014 09/24/96
TITLE: Configuration Tips: PCI, Manhattan S
SUMMARY
This bulletin has been prepared to assist customers with the
selection and installation of PCI devices in their Manhattan S/6200
and Commerce Pro servers.
Most of the information is generally applicable to PCI devices and
is not specific to any version of PCI specifications. Some
information is specific to the Manhattan S/6200 and Commerce Pro
servers. In these cases, the difference will be noted.
This bulletin provides information related to the following systems:
501832 and 503076.
NOTES
BACKGROUND
The Manhattan S/6200 and Commerce Pro servers are designed to
comply with the industry standard PCI bus. This bulletin provides
installation tips that will assist with selecting and installing
PCI adapters and help to avoid configuration issues.
Generally, configuration issues with PCI devices are caused by
one or more of the following problems:
1. PCI Adapters which do not completely support the PCI
specification.
2. Differences between interpretations of the PCI
specification by device designers.
3. Additional features and enhancements added by device
manufacturers, which do not properly interact with
other standard PCI devices.
4. Mixing PCI and ISA adapters in the same system.
5. Limitations within the PCI specification as to the
number of IRQ lines available to PCI devices.
Following the checklist and guidelines below will minimize the
above factors and resolve the largest share of PCI configuration issues.
MANHATTAN S/6200 AND COMMERCE PRO REQUIREMENTS
The Manhattan S/6200 and Commerce Pro servers are designed for
use with three types of adapter boards:
1. 32-bit, 5 volt PCI adapters
2. 32-bit EISA adapters, and
3. 16-bit ISA adapters.
The PCI bus is comprised of the top six adapter slots in the
system. There are two PCI busses in the system, connected
together by a PCI Bridge controller chip. The top two PCI slots
are located on the Primary PCI bus, which is sometimes referred
to as "ahead" of the PCI bridge. The next four PCI slots are
located on the Secondary PCI bus, which is sometimes referred to
as "behind" the PCI bridge. Keep the slot location in mind when
installing PCI devices, because some adapter device drivers do
not support PCI Bridges. If an adapter is not working correctly
when installed on the Secondary PCI bus, try to install the
adapter on the Primary PCI bus. If the adapter works properly on
the Primary PCI bus, contact the manufacturer of the adapter and
obtain a driver that supports PCI Bridges.
Also consider that some of the PCI slots share PCI Interrupt
Request Lines (PCI IRQs) with other PCI slots in the system. The
PCI specifications allow system manufacturers to share PCI IRQs
with multiple PCI slots. However, some adapters do not operate
properly when they are forced to share an IRQ with another
device. Typically, obtaining a later device driver from the
manufacturer will resolve these problems, because most adapter
designers now ensure that their drivers support these
configurations. The table below lists the slots which share PCI
IRQs in the Manhattan S/6200 and Commerce Pro servers. If a PCI
device is not working correctly, try to install it in a slot that
does not share its PCI IRQ.
Pre-Assigned IRQ Settings in Manhattan S/6200 and Commerce Pro
Slot Number Shares IRQ with Slot Number
1 5
2 6
3 Not shared
4 Not shared
5 1
6 2
PCI adapters may be available in 5 volt, 3.3 volt, and universal
(supports both the 5 volt and 3.3 volts) variations. Both 5 volt
and universal adapters can be physically installed in the
Manhattan S/6200 and Commerce Pro servers. A 3 volt adapter can
not be installed. Ensure that all PCI adapters are either 5 volt
or universal.
NOTE: At the time this bulletin was authored, no 3.3 volt or
universal adapters were readily available on the market.
CHECKLIST
When selecting PCI adapters, always ask the following questions:
1. Does the PCI adapter operate correctly in a 32 bit,
5 volt PCI bus slot?
These are the two primary specifications that should
be considered when selecting a PCI adapter. A PCI
adapter that will not operate in a 32-bit, 5 volt PCI
slot will not function in the system.
2. Does the adapter work on both sides of a PCI - PCI
bridge?
As indicated above, some adapters may not work
properly "behind" the PCI Bridge. If the adapter will
not function behind the PCI bridge, it may only be
installed in PCI slot number 1 or 2. Check with the
adapter vendor to ensure that the device will operate
properly in a PCI bridge environment.
3. Does the adapter support PCI IRQ sharing?
If the PCI adapter does not support PCI IRQ sharing,
then it may only be installed in PCI slot number 3 or
4. These slots do not share their PCI IRQ. Check with
the adapter vendor to ensure that the PCI device
supports sharing of PCI IRQs.
As a troubleshooting and performance aid, it is best to share PCI
IRQs of the same device type and manufacturer. The designer of
the device, when writing a driver that shares IRQs, will have the
most knowledge about the manner is which their own devices behave
in a shared environment. AST also suggests that identical
adapters be used in a shared PCI IRQ environment. A driver could
operate incorrectly if two adapters are similar, but not
identical.
CONSIDERATIONS FOR EISA DEVICES
There are three slots provided in the system for EISA bus
adapters. These adapters are configured through the AST System
Configuration Utility.
When installing an EISA adapter into the system, always configure
the EISA adapter prior to installing PCI adapters. EISA adapters
use "static" resources, meaning that once configured through the
AST System Configuration Utility, they will not change without
re-running the utility. The EISA adapter's resources will then be
"sensed" by PCI devices. The PCI device will then attempt to
avoid conflicts with the EISA adapter.
As a general rule, PCI devices should not be configured to share
resources with EISA devices. While there may be cases when such a
configuration is possible, AST does not suggest to configure the
system in this manner.
CONSIDERATIONS FOR ISA LEGACY DEVICES
An ISA Legacy device is a 16-bit ISA adapter, which is not
Plug-and-Play (PnP) capable. This type of device is not aware of
other devices in the system and can not be reconfigured by the
AST System Configuration Utility. Typically, an ISA Legacy
adapter will be configured through switches or jumpers on the
adapter board, or through a special configuration utility from
the device manufacturer.
Legacy ISA adapters are the most troublesome technology to mix in
a system with EISA and PCI devices, because of the inflexibility
of the ISA adapter and the inability of EISA and PCI devices to
"sense" the existence of ISA legacy adapters.
In order to avoid conflicts, you must know the resources used by
the ISA adapter. If you do not know which system resources an ISA
adapter uses, contact the manufacturer of the adapter before
installing the adapter in the system.
Once you have established the resources that will be used,
install the ISA Legacy adapter in the system prior to installing
any EISA or PCI devices. Run the AST System Configuration Utility
and manually add the ISA adapter to the system and lock its
resources. This can be accomplished by either creating a new .CFG
file in the AST System Configuration Utility, or by adding a .CFG
file from the manufacturer if one is available.
NOTE: It is important to understand that by adding information to
the AST System Configuration Utility about ISA Legacy adapters,
EISA and PCI adapters will become "aware" of the existence of the
ISA adapter in the system. However, changing the information in
the utility program will not change the actual configuration of
the ISA Legacy adapter. Additionally, if the information supplied
to the utility is incorrect, the EISA and PCI devices will be
"aware" of the wrong information.
After adding the ISA adapter information to the AST System
Configuration Utility, add EISA adapters and run the AST System
Utility again. Finally, install the PCI devices. Adding devices
in this order will ensure the orderly assignment of resources to
the PCI devices in the system.
CONSIDERATIONS FOR PLUG-AND-PLAY ISA DEVICES
Plug-and-Play (PnP) ISA devices are similar to ISA Legacy
devices, with the addition of "dynamic" resource configuration.
Resources for these devices are typically configured every time
the adapter senses a change in the system's resource. Typically,
the number of system resources variations is limited to a
pre-selected group.
If an ISA board is operating as a PnP device, it will configure
itself to avoid conflicts with other devices in the systems.
However, if the PnP features of the ISA device are disabled, the
device will operate as a standard ISA legacy device and will
exhibit any of the problems noted above concerning ISA legacy products.
Generally, ISA PnP resources can be locked by a utility supplied
by the manufacturer. Contact the device manufacturer to obtain
any utilities that can be used to lock resources and prevent
dynamic reconfiguration. After the ISA PnP configuration has been
locked into place, follow the suggestions above, treating the ISA
PnP device as if it were an ISA Legacy device.
TAN N/A
---------------------------------------------------------------------
The information in this data sheet is subject to change without
notice. AST Research, Inc. shall not be liable for technical or
editorial errors or omissions contained herein; nor for incidental
or consequential damages resulting from the furnishing, performance,
or use of this material. This material contains information protected
by copyright. No part of this material may be reproduced in any form
without prior written consent from AST Research, Inc.
All rights reserved.
---------------------------------------------------------------------