update_dyld_shared_cac... BSD General Commands Manualupdate_dyld_shared_cac...
NAME
update_dyld_shared_cache -- Updates dyld's shared cache
SYNOPSIS
update_dyld_shared_cache [-root directory] [-arch arch] [-force] [-debug]
[-sort_by_name] [-universal_boot]
DESCRIPTION
update_dyld_shared_cache ensures that dyld's shared cache is up-to-date.
Normally, this command never needs to be manually run. Instead, it is
automatically run by launchd when dyld notices the shared cache is out of
date. To prevent the cache from being regeneated during an install or
during development of OS dylibs, dyld will not trigger a shared cache
rebuild if the environment variable DYLD_NO_FIX_PREBINDING is set, or if
the main executable is a setuid binary, or alternate dylibs are loaded
via one of the DYLD_ environment variables.
The dyld shared cache is mapped by dyld into a process at launch time.
Later, when loading any mach-o image, dyld will first check if is in the
share cache, and if it is will use that pre-bound version instead of
opening, mapping, and binding the original file. This results in signif-
icant performance improvements to launch time.
update_dyld_shared_cache scans the directory
/var/db/dyld/shared_region_roots for text files containing paths to mach-
o executables. The full dependencies of all dylibs required by those
executables is used to determine which libraries are commonly used and
should be placed in the shared cache. If one of the text files contains a
path to a dylib, that dylib and its depenents will be forced into the
cache.
update_dyld_shared_cache builds a separate cache file for each architec-
ture. The cache files and a readable text map of the cached are gener-
ated to /var/db/dyld.
You must be root to run this tool.
The options are as follows:
-root directory
This option specifies the root of an OS installation for
which dyld's shared cache should be updated. This allosw you
to update the shared cache on a non-running version of the
OS. The cache files are created in the var/db/dyld directory
of the specified directory.
-arch arch By default update_dyld_shared_cache generates cache files for
all architecture that the current machine can execute. You
can override this behavior by specifying one or more -arch
options and list exactly which architectures should have
their shared caches updated.
-force This option will cause update_dyld_shared_cache to regener-
ated the shared cache files even if they appear to be already
up-to-date.
-debug This option prints out additional information about the work
being done.
-sort_by_name
By default update_dyld_shared_cache assignes a random start
address to each mach-o image in the cache. This option
causes the start addresses to be choosen in path order, thus
subsequent runs will produce the same address layout which
can help reproduce some bugs.
-universal_boot
This option can only be used running on an machine with an
Intel processor. It builds caches that can be used when
booting on an Intel or a PowerPC based machine.
FILES
/var/db/dyld/shared_region_roots directory of text files with paths to
mach-o images used to determine what should be in shared cache.
SEE ALSO
dyld(1)
Darwin March 23, 2007 Darwin
Mac OS X 10.5 - Generated Sun Oct 28 21:03:36 EDT 2007