Alpha/Linux Wiki

The Rawhide family comprises the Dodge, Wrangler, and Durango (AlphaServer 4000 and 4100) and the Tincup and DaVinci (AlphaServer 1200). ¹⁾ Digital sold these SMP servers from May 1996, ²⁾ and they use MCPCIA core logic. ³⁾

Every Rawhide system is built around one system bus, the MCbus: 128 bits wide plus ECC, clocked synchronously with the CPUs and memory, and carrying up to four CPUs, four memory pairs, and four PCI bridges, but no more than ten modules in all. ⁴⁾ Each module has a hardwired MCbus node ID (MID). In Digital's four-CPU Dodge configuration, corresponding to the AlphaServer 4100, the CPUs take four IDs and one bridge module, called Horse, takes two more for its two PCI buses. In the two-CPU Durango configuration, corresponding to the 4000 with its second PCI card cage, a second bridge module takes the IDs of the third and fourth CPUs, for four PCI buses and 16 PCI slots. ⁵⁾ Linux derives each PCI bus's MID from its bus number. ⁶⁾

The AlphaServer 4000 and 4100 are built around a system drawer that fits either a pedestal or a 19-inch cabinet, and which carries the system bus, the PCI I/O, power, and cooling. The two differ only in the drawer: the BA30A drawer of the 4100 has four CPU slots, four memory pairs, and one PCI card cage, while the narrower BA30B drawer of the 4000 has two CPU slots, two memory pairs, and room for a second PCI card cage. Systems could be upgraded in either direction. ⁷⁾

Except where noted, the following comes from the technical summary. ⁸⁾

• Up to four CPUs in the AlphaServer 4100 and two in the AlphaServer 4000; all CPUs in a drawer must be the same type and speed, and slot CPU0 must be populated because the clock is tied to it
• 21164 or 21164A at 300 MHz with 2 MiB of cache, 21164A at 400 or 466 MHz with 4 MiB of cache; later 533 MHz models with 4 MiB and 600 MHz models with 8 MiB of cache were sold ⁹⁾
• 300 MHz CPU modules were built with either CPU: the uncached and 1 MiB and 2 MiB cached 4100 modules (301AA-AB, 302AA-AA, 302AA-AB) and the 2 MiB cached 4000 module (302CA-AB) carry a 21164 (EV5), while the other 300 MHz modules and all 400 and 466 MHz modules carry a 21164A (EV5.6) ¹⁰⁾
• 128-bit data bus with a separate 40-bit command and address bus, clocked synchronously with the CPU: 1 GB/s with a 300 MHz CPU and 1.1 GB/s with a 400 or 466 MHz CPU, 120 ns memory latency, ECC on data and parity on commands and addresses
• Memory in identical pairs of modules, up to four pairs (8 GiB) in the 4100 and two pairs (4 GiB) in the 4000, in 128 MiB, 512 MiB, 1 GiB, and 2 GiB options; the 128 MiB option uses SDRAM and the larger ones EDO DRAM
• The largest pair must be in MEM 0L and MEM 0H, and all pairs are then decoded as that size, with the resulting holes mapped out as bad pages
• Holes fall below the top of memory, and are seen by the operating system, only with three or four pairs of which at least two are smaller than the largest; a system can then have at most two holes ¹¹⁾
• Each system bus to PCI bridge module drives two independent 64-bit PCI buses on a PCI motherboard with eight slots; only PCI bus 0 has an EISA bridge
• Eight PCI slots in the 4100, and up to 16 in the 4000 with the H7150 second PCI card cage option
• Three EISA slots at 8.33 MHz, shared with PCI slots
• One to three power supplies per drawer for N+1 redundancy, three drawer fans plus a fan on each CPU, CD-ROM and floppy in each drawer
• Up to three StorageWorks shelves in the pedestal and up to eight in a cabinet ¹²⁾

• Two 533 MHz CPUs with 4 MiB of ECC cache ¹³⁾
• Six PCI slots, three on each of two peer PCI buses ¹⁴⁾
• Onboard fast narrow single-ended SCSI-2 for removable media, floppy controller, two serial ports, one parallel port, keyboard and mouse controller ¹⁵⁾
• Up to ten internal storage devices in the pedestal, seven of them hot swap StorageWorks disks ¹⁶⁾

There is no MILO for the AlphaServer 1200, 4000, or 4100; Linux boots from the SRM console. ¹⁷⁾ The AlphaServer 4100 SRM console cannot boot from EISA options. ¹⁸⁾ Use the final SRM version, V6.0-4 on the AlphaServer 1200 and V6.1-1 on the 4000 and 4100 (see final SRM versions and Updating firmware).

• The 4100's flash ROM has a write-enable jumper on the PCI motherboard, which Digital's user documentation does not mention but a sticker inside the PCI tray's sliding cover does. Removing the jumper disconnects the flash programming voltage, and firmware can read whether that voltage is present from a status bit. ¹⁹⁾ With the jumper off, the flash is write protected and firmware updates fail. The fail-safe loader floppy works only when the system itself detects corrupt firmware. ²⁰⁾
• The flash is two 1 MB parts: the first holds the SRM console, the OpenVMS and Digital UNIX PALcode, and the fail-safe loader, and the second holds AlphaBIOS, added as a Windows NT requirement. ²¹⁾

Current kernels support Rawhide systems with EV56 (21164A) CPUs (CONFIG_ALPHA_RAWHIDE, or a generic kernel), which boot from SRM with aboot. Linux 6.9 was the last version to support the 4000 and 4100 systems with 300 MHz EV5 (21164) CPU modules; Linux 6.10 removed support for processors older than the EV56 (21164A). ^{22) 23)} The AlphaServer 1200 was sold with 400 and 533 MHz CPUs, ²⁴⁾ which its console reports as EV56. ²⁵⁾

• Rawhide's timer interrupt runs at 1200 Hz. A kernel built with CONFIG_ALPHA_RAWHIDE defaults to HZ of 1200, but a generic kernel defaults to 1024 and must be configured for 1200; a mismatch causes clock skew. ^{26) 27)}
• Rawhide has no byte and word access to I/O space, even with EV56 CPUs. The PCI bridge has linear address windows for it, but they are disabled by default, and the CPU modules decode those addresses as interrupt acknowledge space. ²⁸⁾ Linux reaches Rawhide I/O through sparse space. ²⁹⁾
• Linux sets up the bridge's DMA windows differently from Digital UNIX and OpenVMS, which used a direct-mapped window covering the first 1 GB of memory. ³⁰⁾ Linux uses an 8 MB scatter-gather window at 8 MB for ISA devices, a scatter-gather window of up to 1 GB at 1 GB, and a 2 GB direct-mapped window at 2 GB, ³¹⁾ and gives 64-bit capable devices access to all of memory through the bridge's fixed dual address cycle "Monster Window". ^{32) 33)}
• The AlphaServer 4000, 4100, and 1200 have no IDE controller. ³⁴⁾ Their built-in SCSI controller, for the CD-ROM and other removable media, is an NCR 53C810, ^{35) 36)} shown at hose 1, bus 0, slot 1 in the power-up displays, ^{37) 38)} which uses the sym53c8xx driver. ³⁹⁾ The AlphaServer 1200 reportedly shipped with a PCI QLogic 1040 adapter for the StorageWorks shelf, ⁴⁰⁾ which uses the qla1280 driver and its qlogic/1040.bin firmware file (see Known issues). ⁴¹⁾
• For a serial console, see Using SRM.
• In March 2026 the Debian Ports installer images of December 2025 installed successfully on a two-CPU EV56 AlphaServer 1200 with 1 GiB of memory, once the QLogic firmware had been added to the installer's initrd; the reporter had not yet tried the SMP kernel. ⁴²⁾

• SCSI firmware: Debian's installer images do not include the non-free qlogic/1040.bin firmware that qla1280 needs, so it has to be added to the installer's initrd. ^{43) 44)}
• Memory above 2 GiB: untested with current kernels; the reports conflict (see Conflicting information).

• On the 4100, graphics must go in PCI bus 0, slot 2. ⁴⁵⁾
• The EISA configuration matters even with no EISA cards installed: a configuration written by the Windows NT ECU can prevent an operating system from booting until the UNIX/OpenVMS ECU is run, ⁴⁶⁾ and the ECU must be run again after an SRM update. ⁴⁷⁾
• The AlphaServer 1200 SRM console does not recognize the LSI 53C1010 SCSI controller, and the built-in storage shelf supports only Ultra SCSI speed. ⁴⁸⁾

Digital introduced the drawer approach with the AlphaServer 4100 in May 1996 and extended it to the AlphaServer 4000 5/300 and 5/400 on 4 September 1996. ⁴⁹⁾

Digital's programmer's manual of May 1996 described Rawhide as core logic for EV5, EV56, and EV6 systems, ⁵⁰⁾ and expected a workstation version built from the Dodge enclosure with EV56 CPU modules. ⁵¹⁾ The systems shipped with 21164 and 21164A processors only.

The following sources conflict with each other or with the account given above. They are listed here for further investigation.

• Memory holes
  • AlphaServer 4000/4100 Systems Technical Summary, p. 6: "the memory holes that result are treated as bad pages"
  • Rawhide System Programmer's Manual, Revision 1.4, p. 1-6: "Console firmware only describes existing memory and does not create cluster descriptors for memory holes. A memory cluster is created for each region of contiguous memory."
• Rawhide maximum memory under Linux
  • AlphaServer 4100 Systems and Options Catalog, p. 9: "Tru64 UNIX and OpenVMS systems support a maximum of 8 GB of memory"
  • "RE: Linux on Alpha 7300", John Jemiolo, axp-list, 5 Mar 1999: "if it hads more than 2Gb of memory installed it will fail."
  • "Re: kernel: Bogus pci_unmap_single: dma_addr 0 base 800000 size 800000", Jay Estabrook, axp-list, 11 Dec 2003: "If your RAWHIDE has more than 2GB of memory, then it most likely WILL be a problem at some point."
  • "Installation of etch with d-i daily of 21/10/06 on AS4100 fails", Adrian Zaugg, debian-alpha, 22 Oct 2006: an AlphaServer 4100 with four CPUs and 4 GiB of memory "works fine with sarge".