The 2.6.26 merge window, part 2

Since last week's summary was written, another 3700 changesets have found their way into the mainline git repository. The most significant user-visible changes include:

• New drivers have been merged for Wolfson WM9713 codecs, TI DAVINCI AC97 sound chips, Emagic Audiowerk 2 soundcards, x86 PC speakers (new driver which makes them look like sound cards), Asus AV100 (Xonar DX) sound cards, Micron MT9M001 and MT9V022 cameras, PXA27x Quick Capture cameras, Kworld ATSC 120 tuners, cx23417 MPEG encoders, Integrant ITD1000 tuners, Philips TDA10048HN-based demodulators, Philips SAA7171/3/4 audio/video decoders (the last out-of-tree IVTV driver), Auvitek AU8522 demodulators, Samsung S5H1411-based tuners, framebuffer, keyboard, and mouse virtual devices (for Xen), several Wolfson Microelectronics touchscreens, wireless Xbox 360 controllers, Zhen Hua PPM-4CH transmitters, SPCP8x5 USB to serial adaptors, NCR 53c9x SCSI controllers (replacement driver), Freescale 8610 and 5121 display interface units, Intel 965G/965GM integrated graphics controllers, TI OMAP sound controllers (including the one on the Nokia 810), Eee PC function keys, and Intel IXP4xx Ethernet devices.

• There is now "basic" support for braille screen readers.

• Support for the One Laptop Per Child XO architecture has been merged into the mainline.

• The new virtual files found in /proc/pid/mountinfo provide information on all filesystem mounts visible to the relevant process.

• The new virtual file /proc/vmallocinfo displays information on use of vmalloc space within the kernel.

• The SPARC Niagara architecture now has NUMA support.

• The Xen balloon driver (allowing memory to be added to or removed from virtual guests) has been merged.

• By default, /dev/mem can no longer be used to access RAM; Fedora and Red Hat have applied this patch for years, but now it has found its way into the mainline.

• The KVM paravirtualization subsystem now supports the S/390, PowerPC 440, and ia64 architectures.

• Per-process "securebits" are supported. These bits control how a process's capability bits are managed; the patch is intended to help those who would transition over to a fully capability-based system. See this article for a more detailed description of this feature.

• The getrusage() system call has a new RUSAGE_THREAD option which causes it to return information about the current thread only.

• The device whitelist control group patch (described briefly in this article) has been merged.

• It is now possible to create and use partitions with network block device (NBD) devices.

• The audit subsystem can now test events against the type of the file being operated upon.

• The VFS now makes backing device information available under /sys/class/bdi. Interested people can look at per-device readahead and writeback variables there.

• The FUSE filesystem now supports the creation of shared writable memory mappings.

Changes visible to kernel developers include:

• ioremap() on the x86 architecture will now always return an uncached mapping. Previously, it had taken a more relaxed approach, leaving the caching as the BIOS had set it up. The practical result was to almost always create uncached mappings, but with occasional exceptions. Drivers which depend on a cached mapping will now break; they will need to use ioremap_cache() instead.

• The Video4Linux2 API now defines a set of controls for camera devices; they allow user space to work with parameters like exposure type, tilt and pan, focus, and more.

• On the x86 architecture, there is a new configuration parameter which allows gcc to make its own decisions about the inlining of functions, even when functions are declared inline. In some cases, this option can reduce the size of the kernel's text segment by over 2%.

• The legacy IDE layer has gone through a lot of internal changes which will break any remaining IDE drivers.

• The nopage() virtual memory area operation has been removed; all in-tree code is now using fault() instead.

• The SLUB allocator supports a new sysfs file (/sys/kernel/slab/name/order) which allows system administrators to change the size of page allocations used by the named slab.

• A condition which triggers a warning from WARN_ON will now also taint the kernel.

• The get_info() interface for /proc files has been removed. There is also a new function for creating /proc files:

      struct proc_dir_entry *proc_create_data(const char *name, mode_t mode,
  					    struct proc_dir_entry *parent,
  					    const struct file_operations *proc_fops,
  					    void *data);
  

  This version adds the data pointer, ensuring that it will be set in the resulting proc_dir_entry structure before user space can try to access it.

• The object debugging infrastructure has been merged.

The merge window remains open; tune in next week for (what should be) the final set of changes merged for 2.6.26.

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<quote>
By default, /dev/mem can no longer be used to access RAM; Fedora and Red 
Hat have applied this patch for years, but now it has found its way into 
the mainline.
</quote>
Looking at the latest git, the default is CONFIG_NONPROMISC_DEVMEM=n, 
which means, /dev/mem is set to promiscuous mode, contradictory to quote 
above. Ingo's commit "1f56cf1c58c81f7ecf16f5e99ac4a333d9dc9aea" seems to 
have done that.  Am I missing something?

"The legacy IDE layer has gone through a lot of internal changes which will break any
remaining IDE drivers."

Just to make it clear: the in-tree IDE drivers were updated to match the changes so they
shouldn't break... :-)