2.6.13

Released August 29, 2005 changelog
Execute-in-place support: Traditionally, programs are loaded from disk to memory to be executed. However, the current wave of embedded devices store programs in a ROM/flash chip. XIP allows the kernel executing programs directly from that ROM, without being copied to RAM (saving RAM space), and bypassing the page cache/io scheduler layers (since they're not needed). (LWN article) (commit)
i386 CPU hotplug support: provides i386 architecture support for safely unregistering and registering processors during runtime (commit)
Add /proc/sys/fs/suid_dumpable to provide system-wide control over whether or not set-user-ID and set-group-ID processes produce core dumps. The values accepted are: 0 (default) - traditional behaviour, any process which has changed privilege levels or is execute only will not be dumped. 1 - (debug) - all processes dump core when possible. The core dump is owned by the current user and no security is applied. This is intended for system debugging situations only. Ptrace is unchecked. 2 - (suidsafe) - any binary which normally would not be dumped is dumped readable by root only. This allows the end user to remove such a dump but not access it directly. For security reasons core dumps in this mode will not overwrite one another or other files. This mode is appropriate when adminstrators are attempting to debug problems in a normal environment (commit)
x86 now uses the generic PCI bus setup code for assigning unassigned resources
Voluntary preemption patches
build-time configurable clock interrupt frequency: Now HZ defaults to 250 in x86. 1000 is better for "interactivity" (desktops) and 100 is good for performance (servers) and saves some energy in laptops. (LWN article)
inotify (LWN article) (commit)
Support for the Xtensa architecture: 32-bit architecture used in embedded devices (commit) - (commit) - (commit) - (commit) - (commit)
Improved CFQ IO scheduler: With support for I/O priorities (LWN article) (commit)
kexec and kdump: Kexec allows users to load a new kernel from another running kernel. By preserving the memory contents in a crash scenario, kexec allows to implement kdump. Kdump is able to get a memory dump of the previous kernel, and be used as a debugging tool. (LWN article) (commit)
Runtime selectable TCP congestion algorithm: Allow using setsockopt to set TCP congestion control to use on a per socket basis. (commit) - (commit) (LWN article)
Add several TCP congestion modules: H-TCP commit, TCP Hybla (commit), High Speed TCP (HS-TCP) (commit), TCP Westwood (commit), TCP BIC (commit)
Add Direct Rendering Manager device driver for VIA Unichrome chipsets (commit)
32/64-bit DRM ioctl compatibility: 64 bit architectures running 32 bit software have to be compatible with 32-bit ioctl calls (commit)
Add ACL support for NFSv3 (commit) - (commit) and NFSv4 (commit) - (commit)
New driver for the "trusted computing" (TPM) crap^Wchip (commit)
Removal of the devfs configuration option