At Tue, 7 May 2019 05:50:35 -0400 CentOS mailing list <centos at centos.org> wrote: > > On Tue, 7 May 2019 at 04:06, wuzhouhui <wuzhouhui14 at mails.ucas.ac.cn> wrote: > > > Hi, > > > > Recently, I encountered a interesting phenomenon that CentOS 6.3 > > running as normal even if I (my colleague, actually) installed a > > kernel that build for CentOS 7.x (e.g. kernel-3.10.0-327.el7.x86_64.rpm). > > > > I found kernel is mismatch accidentally when I using "uname -r" to > > check kernel version. So my question is what the harmness we will > > get if I install a el7 rpm into a el6 system? > > > > > Many CentOS-7 packages will not install because they will need dependencies > that the EL-6 does not have. The kernel is different because it is mostly > self-contained and meant to be parallel installed. In most cases, it should > result in an unbootable system because the boot is going to be > dracut+systemd bits and the EL-6 has none of that. And I wonder if the EL7 kernel will even show up as an available kernel. EL7 uses Grub 2 and EL6 uses Grub [1]. *Different* config files. Because (unlike Lilo), grub is not updated in the MBR each time its config is updated (eg installing a new kernel), it is very likely the EL7 kernel rpm install might not touch /boot/grub/grub.conf, since it is expecting to update /boot/grub/grub.cfg instead. I know that when I installed Ubuntu 18.04 as a *second* OS, that even though the /boot file system is shared between CentOS 6 and Ubuntu 18.04 the Ubuntu 18.04 installer did not touch /boot/grub/grub.conf and installed /boot/grub/grub.cfg along side (I manually reinstalled grub 1 and manually hacked /boot/grub/grub.conf to put the Ubuntu 18.04 boot option in). > > > > > > Thanks. > > _______________________________________________ > > CentOS mailing list > > CentOS at centos.org > > https://lists.centos.org/mailman/listinfo/centos > > > > -- Robert Heller -- 978-544-6933 Deepwoods Software -- Custom Software Services http://www.deepsoft.com/ -- Linux Administration Services heller at deepsoft.com -- Webhosting Services