User`s guide

Core Kernel Functionality

• Add support for the implementation of SEEK_HOLE and SEEK_DATA in lseek(). (3.1)

• Add the ! escape character to / in hostname and comm strings in core dumps. (3.1)

• If the value of the sysctl parameter shm_rmid_forced is set to 11, all shared memory objects are

marked for removal with IPC_RMID. As this change breaks POSIX compliance, you need to ensure that

no threads are using the orphaned memory. (3.1)

• Add support for generic I/O power management domains (v8) by introducing common headers, helper

functions, and callbacks to allow platforms to use simple, generic power domains for runtime power

management. (3.1)

• Add system-wide power transitions (system suspend and hibernation) support for generic domains (v5).

Add suspend, resume, freeze, thaw, poweroff, and restore callbacks that are associated with

struct generic_pm_domain objects and have pm_genpd_init() interpret them as appropriate.

(3.1)

• Add wakeup device support for system-sleep transitions. Introduce a new generic power management

domain callback routine, .active_wakeup(). This routine is used during the noirq phase of system

suspend and hibernation to decide how to handle wakeup devices. (3.1)

• Add the ability to set a maximum limit for allowable CPU bandwidth to the process bandwidth controller.

The limit is specified as a quota and a period for a group of processes. (3.2)

• To reduce the performance impact from using i_mutex lock with generic_file_llseek(), an

almost lockless generic_file_llseek() is added to VFS that allows the maximum file size of the file

system to be passed in, instead of always using maxbytes from the superblock. (3.2)

• A boot parameter of the form root=PARTUUID=uuid,PARTNROFF=partition_number_offset

extends the root=PARTUUID=uuid syntax to select the root partition by specifying an integer offset

from a known, unique partition. (3.2)

• Add a fault reporting mechanism to the input/output memory management unit (IOMMU) API. (3.2)

• Allow partition creation from user space and add discard support for loop devices. (3.2)

• When performing AIO, allocate kiocb structures in batches to reduce the CPU overhead of a process

taking and releasing the context lock. (3.2)

• Add support for the tagged files ease-of-use feature in sysfs. (3.2)

• Add a comm change event to the process connector. (3.2)

• Add architecture-independent support for highmem page poisoning and verification to debug-

pagealloc. (3.2)

• Add support for poll() in sysctl so that user-space applications can be notified of changes to

sysctl entries. (3.2)

• The x32 kernel ABI (kABI) allows programs to take advantage of x86-64 features such as a larger

number of CPU registers, better floating-point performance, faster position-independent code shared

libraries, function parameters passed via registers, and faster system-call instructions. The kABI uses

32-bit pointers and avoids the overhead of 64-bit pointers. The program is limited to a 4-GB virtual

address space. However, reducing the memory footprint can also allow a program to run faster. (3.4)

• The nomodule kernel parameter can be used to disable module loading as an alternative to using

sysctl.