Re: root FS questions

From: Walter Roberson (roberson_at_ibd.nrc-cnrc.gc.ca)
Date: 09/09/03 

Date: 8 Sep 2003 22:21:51 GMT

In article <7544aa17.0309081232.27204972@posting.google.com>,
Manoj <manoj23@linuxmail.org> wrote:
:I am new to IRIX so pardon me for ignorance.

:Is it possible to boot IRIX off of a root FS that is residing in some
:part of memory?

No.

:Here are some boot messages that I am trying to understand:

:Irix Release 6.3-Wje-Bonsai4 Ip32 Version 10210236 System V
:Warning: Kernname Environment Variable Not Set By Sash. Runtime Symbol
:Table Not Loaded. Loadable Modules Will Not Be Registered Or Loaded.

You have an O2, which has a prom oddity. Reboot, stop for maintenance, go
into the prom, and give the command resetenv
and the above problem will -likely- go away.

:#Warning: Stray Local 1 Interrupt #1

I'm not sure where that is coming from. Possibly a SCSI termination
error, or possibly a board not seated properly.

:Root On Device 0x2000010 (Fstype Efs)

:What does "Root on Device" mean?

0x2000010 is the combined major and minor device number of the filesystem
it booted off of. The 0x200 part encodes "scsi bus", the next 0 is
unused (AFAIR), and the 010 encodes "Bus 0, device #1, partition #0".

:I have understood from FAQs that IRIX
:doesn't support ramdisks.

It doesn't, but 0x2000010 doesn't have anything to do with ram disks.

:Also,the kernel image that produced the above output had the root FS
:embedded in it.So,was the FS copied to some part of memory and then
:used? I definitely know about linux ramdisks where all of it gets
:copied to memory.So how is this different?

/unix was copied from the rootfilesystem into memory and put into execution.
After that, the only parts of the filesystem that are in memory are
the filesystem headers, the list of active inodes and active blocks (etc.),
the blocks that are actually in use, and the blocks that are in the
filesystem cache as recently in use or anticipated to be needed soon.
Very much the same way as Linux operates in the absence of ram disks. 

-- 
I predict that you will not trust this prediction.

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