8.11.1. Funzionalità di pacchetto kernel Debian
A Debian kernel package installs the kernel image (vmlinuz-version
), its configuration (config-version
) and its symbols table (System.map-version
) in /boot/
. The symbols table helps developers understand the meaning of a kernel error message; without it, kernel “oopses” (an “oops” is the kernel equivalent of a segmentation fault for user-space programs, in other words messages generated following an invalid pointer dereference) only contain numeric memory addresses, which is useless information without the table mapping these addresses to symbols and function names. The modules are installed in the /lib/modules/version/
directory.
The package's configuration scripts automatically generate an initrd image, which is a mini-system designed to be loaded in memory (hence the name, which stands for “init ramdisk”) by the bootloader, and used by the Linux kernel solely for loading the modules needed to access the devices containing the complete Debian system (for example, the driver for SATA disks). Finally, the post-installation scripts update the symbolic links /vmlinuz
, /vmlinuz.old
, /initrd.img
and /initrd.img.old
so that they point to the latest two kernels installed, respectively, as well as the corresponding initrd images.
Most of those tasks are offloaded to hook scripts in the /etc/kernel/*.d/
directories. For instance, the integration with grub
relies on /etc/kernel/postinst.d/zz-update-grub
and /etc/kernel/postrm.d/zz-update-grub
to call update-grub
when kernels are installed or removed.
8.11.2. Installare con dpkg
Using apt
is so convenient that it makes it easy to forget about the lower-level tools, but the easiest way of installing a compiled kernel is to use a command such as dpkg -i package.deb
, where package.deb
is the name of a linux-image package such as linux-image-3.16.7-ckt4-falcot_1_amd64.deb
.
I passi di configurazione descritti in questo capitolo sono base ma funzionano sia per un sistema server sia per una postazione di lavoro e possono essere duplicati massivamente con modalità semi-automatiche. Tuttavia non sono sufficienti per fornire da soli un sistema completamente configurato. Alcune parti necessitano ancora di configurazione, cominciando con i programmi di basso livello conosciuti come «servizi Unix».