Hi, On Tue, Oct 23, 2012 at 08:45:25PM -0700, Jonathan Nieder wrote: > Dave Jones wrote: > > Can the wheezy s390x kernel be saved as an NSS? If so, how? > Based on [1], it looks like the answer is currently no, based on the > following line in the kernel config file: > > # CONFIG_SHARED_KERNEL is not set > > The description of that option says > > Select this option, if you want to share the text segment of the > Linux kernel between different VM guests. This reduces memory > usage with lots of guests but greatly increases kernel size. > > You can build a custom kernel using that option if you wish. It works > like this[2]: > > $ apt-get source linux > # apt-get install build-essential fakeroot > # apt-get build-dep linux > $ cd linux-<version> > $ fakeroot debian/rules source > $ fakeroot make -f debian/rules.gen setup_s390_none_s390x
as we're talking about s390x here that would be setup_s390x_none_s390x. > $ cd debian/build/build_s390_none_s390x Same here. > $ scripts/config --disable DEBUG_INFO > $ scripts/config --enable SHARED_KERNEL That's «../source_none/scripts/config». > $ cd ../../.. > $ fakeroot make -f debian/rules.gen binary-arch_s390_none_s390x And again s390x_none_s390x instead of s390_none_s390x. I just did the recompilation. AFAICS the kernel size is indeed increased quite a bit. We currently have: -rw-r--r-- root/root 6303232 2012-10-22 15:36 ./boot/vmlinuz-3.2.0-4-s390x With SHARED_KERNEL on and DEBUG_INFO off as above: -rw-r--r-- root/root 7945728 2012-10-25 21:53 ./boot/vmlinuz-3.2.0-4-s390x So a NSS shareable kernel is 1.26 times larger than a plain one. And I fear that the additional bits cannot be discarded at runtime neither, but I cannot test this right now. Interestingly enough the kernel is already in its plain form 2.23 times bigger than an amd64 build of vmlinuz-3.2.0-3-amd64. Kind regards Philipp Kern > [1] http://www.vm.ibm.com/linux/linuxnss.html > [2] http://kernel-handbook.alioth.debian.org/ch-common-tasks.html -- To UNSUBSCRIBE, email to debian-s390-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20121025221758.ga22...@hub.kern.lc
