[rescue] rescue Digest, Vol 94, Issue 17: response to > 7. Re: Soliars, libc_psr.so.1, where does it come from? (Jerry Kemp)

Gary Sloane gksloane at hotmail.com
Tue Sep 28 10:25:36 CDT 2010

Jerry -

The following should tell you all you need to know about libc_psr_hwcap1.so.1
and libc_psr.so.1...


> Recently i have installed a Sun OS 10 on ultra45, when check the file
> system with command df -k appears this FS :
> */platform/sun4u-us3/lib/libc_psr/libc_psr_hwcap1.so.1
>                     4033206  134824 3858050     4%
> /platform/sun4u-us3/lib/libc_psr.so.1
> /platform/sun4u-us3/lib/sparcv9/libc_psr/libc_psr_hwcap1.so.1
>                     4033206  134824 3858050     4%
> /platform/sun4u-us3/lib/sparcv9/libc_psr.so.1
> *
> Why..?
> I hope can you help me.
> Greetings.
> Marcos

hello Marcos,

take a look at this document it explains why and what these are:

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.

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