[SUMMARY] Solaris 10, strange df output !?

From: Pascal Grostabussiat <pascal_at_azoria.com>
Date: Mon Jul 31 2006 - 05:05:57 EDT
First of all, many thanks to Casper Dik and Ilya Voronin for their answers:

According to Casper, those mounting-points correspond to architecture 
specific optimized versions of the libraries and they are mounted on top 
of the originals to override them. That's because the image is 
architecture neutral and the optimized libraries are determined at 
runtime. In my case I am running Solaris 10 on a T2000 machine which is 
likely the reason for those optimization. Casper was however unsure as 
to why this had been done that way.

Ilya pointed me to the following Sun Solve document containing some more 


Since you need an account to access that document I paste the contents 


Why do libc_psr_hwcap1.so.1 and libc_psr.so.1 show as mount points?

The purpose of this document is to help explain why the mount points 
detailed below are shown from df(1M) and mount(1M).

Under some circumstances, such as an operating system upgrade or patch 
installation, the following mount points may be shown from df(1M) and 

mounted on
mounted on

An example of what could create these mounts is an OS upgrade to Solaris 
10 (Update X) or the installation of patch 122750-XX.
Note: these are just examples - it may not be restricted to this /

These mounts will not show on all systems as the change is hardware 
specific, which the patch and OS are not.


Why is this?

The mount points detailed have been created intentionally by 
engineering. In basic terms, they are a platform specific enhancement to 
ensure full application performance is achieved. This is done by 
changing the way the Operating System fully utilizes the  potential of 
the CPU for the platform.

The libc_psr libraries implement platform-specific, optimized versions 
of block copy and move routines from libc, such as memcpy(). On 
UltraSPARC machines, these routines are coded in assembler, and use 
block load and store ASI's, prefetch, and other tricks for better 

This is enabled using the HWCAP feature of the linker; see the linker 
guide for details (http://docs.sun.com/app/docs/doc/817-1984). 

The alternate routines live in the libc_psr_hwcap1.so.1 library.  At 
boot time, the libc_psr_hwcap1.so.1 library is loop-back mounted onto 
the libc_psr path using a combination of the moe(1) utility, and mount 
-F lofs, invoked from the start method of the 
svc:/system/filesystem/root service (/lib/svc/method/fs-root).  As this 
is a loopback mount, no disk space is waisted.
This is the only way that this enhancement can be implemented, and at 
this time will not be changed. Disabling this functionality is not 
possible or supported.
sunmanagers mailing list
Received on Mon Jul 31 05:06:31 2006

This archive was generated by hypermail 2.1.8 : Thu Mar 03 2016 - 06:44:00 EST