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 * Q. I am trying to use devfs with devfsd and grub-install is complaining.
   ''' A. If you have old /dev/hd? entries in your /boot/grub/devices.map grub-install will complain. The solution is to delete the devices.map and rerun grub-install '''

 * DebPkg:devfsd is a small daemon that sets up all of the old /dev entries for compatibility with older programs.

["Kernel"] > FAQ

Boot manager issues

In case of ["LILO"] boot manager:

In case of ["Grub"] boot manager:

  • Q. I just upgraded to the 2.4 kernel from a 2.2 or 2.0 series kernel, and I get an kernel panic error saying /root= missing, halfway into the boot. My old kernel still works without any problems though. What's going on?
    • A. The Debian 2.4 series kernels use an initial RAM disk (initrd) to load part of the kernel at boot time ... This is an error that could show up if you've used dist-upgrade to migrate from a previous Debian release (i.e. Potato).
      • ["LILO"] Add the appropriate initrd=/boot/initrd-2.4 to your lilo.conf and rerun lilo.
      • ["Grub"] Modify the /boot/grub/menu.lst to include the proper initrd= setting. You do not need to re-run install-grub

?Anchor(troubleshooting)

Troubleshooting/Debugging

?Anchor(kernel-oops)

Kernel Oops

The 'oops' refers to the message printed by the Linux kernel when an unforseen condition occurs. Such incidents should be reported to the Linux kernel developers. Information on how to do so comes with the Linux kernel sources. You may consider to install the Debian package '[http://packages.qa.debian.org/k/kerneloops.html kerneloops]' to automate the reporting.

?Anchor(configuration-files)

Where is the kernel configuration file ?

The kernel configuration file of Debian Official kernel are available in /boot, named after the kernel release, like /boot/config-2.6.18-6-486, or /boot/config-$(uname -r).

All the kernel configuration files, which were used to build the official Debian's binary kernel images from the linux-2.6 source package are available from [http://merkel.debian.org/~jurij/].

?Anchor(new-features)

New features

kernelnewbies.org has summaries of new features in kernels :

?Anchor(new-features-in-lenny)

New features in Lenny

Summary of new kernel features in Lenny

mount -t fat -o flush

Avoid data loss if usb devices (mp3 players) are withdrawn improperly

 CPU hotplugging

 dynimically reconfigure Virtual computer

GCC stack protection

is it active in Debian ?

  • .. to be written

Details :

2.6.25

2.6.25 includes support of a new architecture (MN10300/AM33) and the widely used Orion ?SoCs, a new interface for more accurate measurement of process memory usage, a 'memory resource controller' for controlling the memory usage of groups of processes, realtime group scheduling, a tool for measuring high latencies called latencytop , ACPI thermal regulation, timer event notifications through file descriptors, an alternative MAC security framework called SMACK, a ext4 update, BRK and PIE-executable address space randomization, RCU preemption support, FIFO spinlocks in x86, EFI support in x86-64, a new network protocol called CAN, initial ATI r500 DRI/DRM support, the beginning of the end for tasks stuck in D state, improved device support and many other small improvements. more on [http://kernelnewbies.org/Linux_2_6_25]-~.

2.6.24

2.6.24 includes CPU "group scheduling", memory fragmentation avoidance, tickless support for x86-64/ppc and other architectures, many new wireless drivers and a new wireless configuration interface, SPI/SDIO MMC support, USB authorization, per-device dirty memory thresholds, support for PID and network namespaces, support for static probe markers, read-only bind mounts, SELinux performance improvements, SATA link power management and port multiplier support, Large Receive Offload in network devices, memory hot-remove support, a new framework for controlling the idle processor power management, CIFS ACLs support, many new drivers and many other features and fixes. ~-more on [http://kernelnewbies.org/Linux_2_6_24]-~.

2.6.23

2.6.23 includes the new, better, fairer CFS process scheduler, a simpler read-ahead mechanism, the lguest 'Linux-on-Linux' paravirtualization hypervisor, XEN guest support, KVM smp guest support, variable process argument length, make SLUB the default slab allocator, SELinux protection for exploiting null dereferences using mmap, XFS and ext4 improvements, PPP over L2TP support, the 'lumpy' reclaim algorithm, a userspace driver framework, the O_CLOEXEC file descriptor flag, splice improvements, new fallocate() syscall, lock statistics, support for multiqueue network devices, various new drivers and many other minor features and fixes. ~-more on [http://kernelnewbies.org/Linux_2_6_23]-~.

2.6.22

2.6.22 includes an optional, more SMP-friendly SLUB allocator ), new and much better wireless and firewire stacks, a new architecture called Blackfin, a LVM-for-flash-storage-devices called UBI, event notifications through file descriptors , the POSIX-draft utimensat() syscall, the 'TCP Illinois' and 'YeAH-TCP' congestion control algorithms, IPV6 Optimistic Duplicate Address Detection, AF_RXRPC socket support, relocatable x86-64 kernel support, improvements to the CFQ I/O scheduler, more process footprint information in /proc, various new drivers and many other improvements. ~-more on [http://kernelnewbies.org/Linux_2_6_22]-~.

2.6.21

2.6.21 improves the virtualization features merged in 2.6.20 with VMI, a paravirtualization interface that will be used by Vmware (and maybe -probably not- Xen) software. KVM does get initial paravirtualization along with live migration and host suspend/resume support. 2.6.21 also gets a tickless idle loop mechanism called "Dynticks" , a feature built in top of "clockevents" which unifies the timer handling and brings true high-resolution timers. Other features are: bigger kernel command-line, optional ZONE_DMA; support for the PA SEMI PWRficient CPU, for a Cell-based "celleb" architecture from Toshiba, better PS3 support: support for NFS IPv6, IPv4 <-> IPv6 IPSEC tunneling support, UFS2 write support, kprobes for PPC32, kexec and oprofile for ARM, public key encryption for ecryptfs, Fcrypt and Camilla cipher algorithms, NAT port randomization, audit lockdown mode, many new drivers and many other small improvements.~-more on [http://kernelnewbies.org/Linux_2_6_21]-~.

2.6.20

With 2.6.20, Linux joins the virtualization trend. This release adds two virtualization implementations: A full-virtualization implementation that uses Intel/AMD hardware virtualization capabilities called KVM and a paravirtualization implementation that can be used by different hypervisors (Rusty's lguest; Xen and VMWare in the future, etc). This release also adds initial Sony Playstation 3 support, a fault injection debugging feature , UDP-lite support, better per-process IO accounting, relative atime, support for using swap files for suspend users, relocatable x86 kernel support for kdump users, small microoptimizations in x86 (sleazy FPU, regparm, support for the Processor Data Area, optimizations for the Core 2 platform), a generic HID layer, DEEPNAP power savings for PPC970, lockless radix-tree readside, shared pagetables for hugetbl, ARM support for the AT91 and iop13xx processors, full NAT for nf_conntrack and many other things.~-more on [http://kernelnewbies.org/Linux_2_6_20]-~.

2.6.19

Linux 2.6.19 includes the clustering GFS2 filesystem ; Ecryptfs the first experimental version of EXT4 (aimed at developers), support for the Atmel AVR32 architecture, sleepable RCU, improvements for NUMA-based systems, a "-o flush" mount option aimed at FAT-based hotpluggable media devices (mp3), physical CPU hotplug and memory hot-add in x86-64, support for compiling x86 kernels with the GCC stack protection, vectored async I/O , Netlabel subsystem, allow to disable compilation of the block layer, IDE Parallel-ATA drivers based in libata, Granular IPSec associations for use in MLS environments, add the Netlabel subsystem, Mobile IPv6 (RFC 3775), some new drivers, improved support for many already existing drivers, and many other things.~-more on [http://kernelnewbies.org/Linux_2_6_19]-~.

?Anchor(new-features-in-etch)

New features in Etch

2.6.18 (Debian Etch's version), and Previous versions

see [http://kernelnewbies.org/Linux26Changes]


See also: