Appendix B. Installing Linux on Digital/Compaq Alpha Systems
In 1992, Digital Equipment Corporation (later purchased by Compaq) introduced a 64-bit, superscaler, RISC-based architecture called the Alpha that won impressive reviews in the industry for speed. Linux is an attractive alternative to the traditional operating systems shipped with the Alpha, especially for the older Alpha hardware now being sold into the marketplace. But installation varies from system to system because the Alpha evolved rapidly and has been shipped over the years with a wide variety of hardware and firmware (startup programs stored in ROM). This appendix is an introduction to the main issues and tasks in installing Linux, but you will also need to read the documents for Linux installation and your hardware carefully, and show a somewhat adventurous willingness to experiment.
A discussion of Alpha systems would have to cover years of hardware evolution from the older style UDB system to the current DS and ES series systems, as well as standard OEM configurations. Because there are so many different BIOS configurations and boot options, it's impossible to give detailed installation instructions for every type of Alpha system. We hope this discussion will be a guide to help users who are new to the Alpha architecture understand what to do when installing a new system.
TIP: This discussion does not cover VAX, MIPS, AMD, or Intel CPU-based systems or hardware that share peripheral and packaging technologies with Alpha-based systems. We will focus only on the installation of Linux on Alpha systems and components manufactured by Compaq or licensees of Alpha technology, such as Samsung Semiconductor, API NetWorks Inc., or Mitsubishi Semiconductor.
B.1. Alpha History and Status
In 1992, Digital Equipment Corporation, also known as DEC or Digital, introduced the Alpha with support for seven hardware platforms, three operating systems, multiple networking protocols, and multiple language compilers.
The Alpha constitutes the largest engineering project ever undertaken by Digital, involving more than 30 engineering groups spread across 10 countries. It was not the first RISC-based semiconductor that Digital produced, but it was the first that Digital decided to sell in the open market. Digital Semiconductor (DS) was created as an internal business group to manufacture, sell, and distribute Digital's semiconductors on the merchant market.
To keep up with demand and evolving semiconductor manufacturing technology, Digital outsourced manufacturing of the Alpha semiconductor, which included agreements with Samsung Electronics and Mitsubishi Electric to manufacturer current and future implementations of the Alpha semiconductors. In addition, the agreements granted Samsung and Mitsubishi licenses to market, sell, and distribute Alpha semiconductors worldwide and included joint development projects related to the Alpha semiconductor family.
The relatively small installed base of Alpha systems, and the fact that most existing systems are "development platforms" that allow tinkering and tuning supported by massive archives of hardware documentation, have encouraged continued development of Alpha chipsets. However, it also makes it hard for Linux developers to gather the wide range of systems under one simple installation procedure.
Compaq had its eyes set on having its own enterprise server architecture and operating system — an alternative to Microsoft and Intel. On January 26, 1998, Digital and the Compaq Computer Corporation announced a $9.6 billion-dollar merger where Digital became a wholly owned subsidiary of Compaq. DS came with the multibillion dollar package, and the name Digital was absorbed into Compaq.
Since the takeover Compaq has continued to develop the Alpha chip with the EV7 slated for introduction in 2002. Unfortunately Compaq has also announced that development will be stopped with EV7 and that future Compaq high end servers will utilize Intel's IA64 architecture instead of Alpha.
To summarize, Alpha architecture is a superscaler, open-industry standard, 64-bit, RISC-based architecture that is engineered by Compaq and manufactured in volume by Samsung and its subsidiaries.
B.1.1. The Linux Port and Distributions
The Alpha port of Linux did not happen overnight. It began as a rather humble patch to the Linux kernel. The first kernel patch was developed with funding and support from Digital. Even with all the patches to the kernel, most of the distributions' drivers and "userlands" were not 64-bit clean. (In other words, programs assuming a 64-bit word might fail because of hidden 32-bit calculations or declarations in underlying software.) The mainstream kernel itself was not 64-bit clean until the 2.1.x development kernels. When development work on the 2.1.x kernels began, the Alpha port was adopted directly into the Linux kernel source tree. At this stage, the Alpha port of the Linux kernel was supported directly by the mainstream kernel distributions.
During the development efforts of the 2.1.x kernel, the Linux kernel and its drivers were made 64-bit clean. Most of the unaligned traps in the kernel were corrected, and the userland became much more 64-bit aware. At this time, Red Hat Software, Inc., quickly saw that the server and workstation processor market was headed in the direction of 64-bit architectures and released a full Alpha port of their Linux distribution, Red Hat Linux 2.1. Other distributions followed, including Debian and SuSE. The distributions are described in the following list:
There are five classes of Alpha CPU: the 21064, 21066, 21164, 21264 and the upcoming 21364. The 21064 and 21066 classes are both first-generation Alpha architectures, but the 21066 incorporates functions normally supplied on support chips into the CPU itself, creating special platform characteristics and requirements. The 21164 and 21264 classes represent second- and third-generation chip architectures, respectively. Various chip architectures have been coupled with different system buses and interfaces, which subdivide the CPU types into different families of Alpha computers ranging from desktop systems to supercomputing clusters.
We will not discuss embedded systems and display terminal uses of Alpha CPUs here.
For purposes of installing Linux from a CD-ROM distribution, the subdivisions differ in the support that the Linux kernel provides for the features of the chips and in system assemblies and interfaces that use those features. If you cannot boot a kernel that appears to match your system, try a similar kernel from a related system or try a generic kernel. And, if that does not work, go to the AlphaLinux FTP site and try an earlier kernel or a later, developmental kernel. For the most part, however, your installation should be straightforward if you have selected the right image files to load and install Linux.
B.1.3. Sources of Information
Before you choose a Linux distribution, use the considerable resources about Linux and Alpha on the Internet. A wealth of detailed hardware information about Alpha chips and platforms designed to support it are available for downloading and printing, including technical manuals that would be expensive to purchase or completely unavailable through marketing channels. Be aware that much useful documentation may be supplied by a different vendor than the manufacturer of your CPU or system, and from other distribution resources as well.
You should probably have at least a hardware manual for your system, which will describe hardware configuration and the use of the firmware consoles for your system, as well as provide useful error codes and diagnostics if there are difficulties. There will be an appendix near the end of each of Digital's system or evaluation board manuals that lists related documents, some of which are also useful. The document numbers will identify the files that you want from the Alpha library archive.
There are web sites providing FAQ files and other useful information for some specific Alpha systems as well.
You should also have the installation documents and addenda for your CD-ROM installation and information regarding any bugs and fixes for the distribution you are installing. Where your documentation is incomplete or describes a generic Linux installation, rather than the specific Linux Alpha installation, you may want to use the following sequence as a guide for installation.
Following is a partial list of important Internet sources for Alpha hardware information and information about installing Linux on Alpha systems.
B.1.3.1. AlphaLinux sites
B.1.3.2. AlphaLinux mailing lists
B.1.4. Minimum Hardware
You can run Linux on Alpha systems using as little as 8 MB of RAM, but most installation programs, like the Red Hat installer, require a minimum of 32 MB. The minimum disk space for the installation is 170 MB. To run the full X Window System and a desktop comfortably and have adequate storage for applications, you need a minimum of 16 MB RAM and 500 MB of hard-disk storage.
Many users of more recent Linux distributions have found that 24 MB or 32 MB of RAM is required to complete the installation. While it should still require no more than 16 MB to run Linux on a properly configured Alpha system (with a kernel compiled to support just that system's features), you may need more memory to install some distributions. An alternative is to install an earlier, smaller kernel.
Installation takes a huge amount of RAM because of the combined memory requirements of the bootstrap loader, Milo (if used) and the loading Linux kernel image, not because of the memory requirements of the Linux kernel itself. If you cannot complete your initial installation, you can also try to use an earlier and smaller Milo to boot your Linux distribution or a Milo that has been stored in nonvolatile RAM. You can select compact applications to conserve memory and storage. For more information, see http://www.linuxalpha.org.
B.1.5. IDE/ATAPI Drive Support
Some Alpha systems, especially those intended for use as network servers, do not support IDE or ATAPI drives. We recommend a fast SCSI drive as a basic system element, whether installed internally or attached externally. If your system has a free PCI slot, you can add a current PCIbus ATAPI/EIDE controller card supported by Linux in order to attach cheaper EIDE hard disks or fast CD-ROM drives. But you will most likely not be able to boot from this device because the SRM console will not have a driver for it.
Early Alpha systems provided 10 Mbps SCSI-2, and some of the latest Alpha system boards provide "fast and wide" 160 Mbps SCSI-3. The very earliest board (Jensen) provided an Adaptec 1740 ISA bus controller, but most SCSI controllers are from either the NCR (LSI Logic) or Adaptec family of controllers. These were considered high-performance controllers when adopted.
B.1.6. Mice and Serial Ports
Problems are often reported during Linux installations in connecting a serial mouse to the system. Some Linux installation programs map device definitions to the serial ports incorrectly during kernel configuration. Most of these complaints involve autodetection of a mouse installed on the first serial port. We recommend that you install a three-button PS/2-type mouse, if your system has a PS/2 hardware port, rather than a serial mouse. Moreover, do not put a modem on serial port 1, because Milo will echo its output to serial port 1 with strange results.
Copyright © 2003 O'Reilly & Associates. All rights reserved.