path: root/Documentation/voyager.txt
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authorLinus Torvalds <>2005-04-16 15:20:36 -0700
committerLinus Torvalds <>2005-04-16 15:20:36 -0700
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tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/voyager.txt
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+Running Linux on the Voyager Architecture
+For full details and current project status, see
+The voyager architecture was designed by NCR in the mid 80s to be a
+fully SMP capable RAS computing architecture built around intel's 486
+chip set. The voyager came in three levels of architectural
+sophistication: 3,4 and 5 --- 1 and 2 never made it out of prototype.
+The linux patches support only the Level 5 voyager architecture (any
+machine class 3435 and above).
+The Voyager Architecture
+Voyager machines consist of a Baseboard with a 386 diagnostic
+processor, a Power Supply Interface (PSI) a Primary and possibly
+Secondary Microchannel bus and between 2 and 20 voyager slots. The
+voyager slots can be populated with memory and cpu cards (up to 4GB
+memory and from 1 486 to 32 Pentium Pro processors). Internally, the
+voyager has a dual arbitrated system bus and a configuration and test
+bus (CAT). The voyager bus speed is 40MHz. Therefore (since all
+voyager cards are dual ported for each system bus) the maximum
+transfer rate is 320Mb/s but only if you have your slot configuration
+tuned (only memory cards can communicate with both busses at once, CPU
+cards utilise them one at a time).
+Voyager SMP
+Since voyager was the first intel based SMP system, it is slightly
+more primitive than the Intel IO-APIC approach to SMP. Voyager allows
+arbitrary interrupt routing (including processor affinity routing) of
+all 16 PC type interrupts. However it does this by using a modified
+5259 master/slave chip set instead of an APIC bus. Additionally,
+voyager supports Cross Processor Interrupts (CPI) equivalent to the
+APIC IPIs. There are two routed voyager interrupt lines provided to
+each slot.
+Processor Cards
+These come in single, dyadic and quad configurations (the quads are
+problematic--see later). The maximum configuration is 8 quad cards
+for 32 way SMP.
+Quad Processors
+Because voyager only supplies two interrupt lines to each Processor
+card, the Quad processors have to be configured (and Bootstrapped) in
+as a pair of Master/Slave processors.
+In fact, most Quad cards only accept one VIC interrupt line, so they
+have one interrupt handling processor (called the VIC extended
+processor) and three non-interrupt handling processors.
+Current Status
+The System will boot on Mono, Dyad and Quad cards. There was
+originally a Quad boot problem which has been fixed by proper gdt
+alignment in the initial boot loader. If you still cannot get your
+voyager system to boot, email me at:
+The Quad cards now support using the separate Quad CPI vectors instead
+of going through the VIC mailbox system.
+The Level 4 architecture (3430 and 3360 Machines) should also work
+Dump Switch
+The voyager dump switch sends out a broadcast NMI which the voyager
+code intercepts and does a task dump.
+Power Switch
+The front panel power switch is intercepted by the kernel and should
+cause a system shutdown and power off.
+A Note About Mixed CPU Systems
+Linux isn't designed to handle mixed CPU systems very well. In order
+to get everything going you *must* make sure that your lowest
+capability CPU is used for booting. Also, mixing CPU classes
+(e.g. 486 and 586) is really not going to work very well at all.