site_archiver@lists.apple.com Delivered-To: darwin-dev@lists.apple.com Suppose I have a binary built with ppc, i386 and x86_64 architectures. -- Terry _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.appl... On Mar 11, 2009, at 11:36 PM, Jim Correia wrote: Also suppose that on a particular OS release, I want to ensure that when I exec that binary, the i386 variant runs, not the x86_64. For bundled applications, I can influence this through the LS keys. Before I exec the tool, I've tried setting sysctl.proc_exec_affinity to CPU_TYPE_X86 but the 64-bit version is executed. (Setting the affinity to ppc seems to work.) Am I overlooking something? Yeah, the affinity sysctl was a kluge that worked due to single threading of forks from finder, and it also dealt with child binaries preferences being inherited from the parent process through multiple children and grandchildren. It was primarily intended to programs which had PPC versions of plugins for which there were not yet any Intel equivalents. It wasn't really possible for the approach to be reasonably generalized to arbitrary architectures, both because it really failed to support the ideas necessary for that, and because Moores law is no longer a law. The place where this would be important today is on a machine capable of running 64 bit Intel binaries, but for which only the system framework is available, and not other frameworks. Since we changed the 64 bit binary cpu type number by adding a "has 64 bit frameworks bit" to it, when we added framework support, if you link a new binary, the 386 version of the binary is going to be preferred by the older version of the OS anyway, so you'd be solving a problem that doesn't exist in the first place. The other place it could be important is if you ported over your 32 bit KEXT or daemon that talked to it, and decide, for whatever reason that you wanted to still communicate ponter and long values between it and user space instead of using sized types. But you could also LIPO at install time with your install tool or the binary itself when it saw the results of the uname(2) system call, or you could also write a small script to wrap the use of the arch(1) command, or you could use the posix_spawn(2) extensions documented in posix_spawnattr_setbinpref_np(2) to reexec yourself, if you didn't mind running the 64 bit binary, saying "whoops! I should be 32 bit!" and restarting yourself with a different preference. This email sent to site_archiver@lists.apple.com