Sunday, July 17, 2011

Hiding the boot device from an OS

Suspecting a bug in SCSI subsystem, I was wondering how to prevent an OS from detecting the device it's booting from. At first it sounds weird, but it's possible for most of OS/distributions in the SPARC (and probably PPC) world, because they
  • boot  init scripts from a RAM disk
  • use IEEE 1275 device tree to find out available devices *
*) with exception of  Linux. At least the Linux uniform IDE driver tries to detect a hardware by probing.

For FreeBSD, NetBSD, OpenBSD and Solaris it's possible to hide the boot device from the OS install CD with the following commands:

ok cd scsi " unknown" name device-end
ok boot /unknown/sd@6,0:f

Use the Forth, Luke!

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