ARC

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The ARC Standard

was born in the early 90s as part of the Advanced Computing Environment initiative. It standardized certain hardware features and the ARC firmware environment. What all ARC implementations have in common is their strict non-compliance to the ARC standard, so the ARC Standard document should be taken with a shovel of salt.

Endianess

For the ease of Microsoft's Windows NT effort the ARC standard defines the byte order to be little endian only. SGI systems where ARC is called ARCS violate that by being big endian.

Network Booting

The ARC Standard mandates network booting of an operating system via BOOTP/TFTP or alternatively DCL/RIPL. Most implementations comply to that with a varying degree of buggyness; the exception is the Olivetti M700-10 where network booting is not supported at all.

Machine doesn't download the kernel when I try to netboot

This problem has been observed with the ARC firmware of SNI RM200 and SGI IP22.

The boot client is replying to the BOOTP packets (may be verified using a packet sniffer like tcpdump or ethereal), but doesn't download the kernel from your BOOTP server. This happens if your boot server is running a kernel of the 2.3 series or higher. The problem may be circumvented by doing an

  echo 1 > /proc/sys/net/ipv4/ip_no_pmtu_disc"

as root on the boot server. Alternatively you can also add this setting to /etc/sysctl.conf.