At Sun, 3 Apr 2005 12:24:38 +0200, Bastian Blank wrote: > [1 <text/plain; utf-8 (quoted-printable)>] > On Sat, Apr 02, 2005 at 09:37:54PM +0900, GOTO Masanori wrote: > > > > I think the simple shell script wrapper controlling HWCAP_MASK can > > > > achieve the original request by Bastian. > > > No, it does not. You have to replace any binary with this wrapper, even > > > /sbin/init. > > Hmm, I have not understood why you want to use such mechanism. What's > > the merit of your proposal? Which application are you focusing in > > this proposal? > > Okay, lets show some scenarios: > > 1. Enable specific optimizations: for example SSE. > 2. Disable tls: run XenLinux or UML, both supports linux 2.6 but no TLS. > 3. Disable i686 optimization: testing of the other libs. > 4. Enable tls: RedHat shipped 2.4 kernels with TLS-Support. > > 1 and 4 can be done with LD_LIBRARY_PATH, as it is not critical. > 3 can be done with LD_LIBRARY_PATH which pulls the unoptimized libs > before the optimzed. > 2 is missing, LD_ASSUME_KERNEL needs to be _always_ defined, it is not > even possible to start a shell without. > > The current glibc defines a generic interface for 1 and 3 but noone > is able to show me how to use it and my checks of the source showed > that 3 is not able with the hwcap machanism.
Note that 3 can be disabled on debian: /etc/ld.so.nohwcap. Tough it disables all hwcap mechanisms, we cannot select each hwcap bits currently. > 2 and 4 is done via an explicit check for the kernel version. For me, it seems this issue mixes three different terms: (1) tls (controlled by LD_ASSUME_KERNEL) (2) processor platform AT_PLATFORM (no generic way to control) (3) processor capability AT_HWCAP (controlled by LD_HWCAP_MASK) Debian glibc i686 provides three libraries: /lib, /lib/tls, /lib/tls/i686/cmov. (3) can be hidden by controlling (2), and (2) can be hidden by controlling (1). Is it enough to fix your problem using /etc/ld.so.nohwcap, LD_ASSUME_KERNEL and LD_HWCAP_MASK? > > if you have experience to modify > > the code for specific architecture's capability to get performance > > improvement like HPC application, you would nod some parts of my > > previous mail. > > I have none, I only raised that as an example because people asked for a > generic solution for that problem. > > We have even some library packages in the archive which provides such > optimized libs, they use its one hack to enable optimized libs. Do you have any actual examples? Regards, -- gotom -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]