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A long ago, in days of yore, it all began with a god named Thor.
There were vikings and boats and some plans for a Linux kernel
header. Unfortunately, a single 8-bit field was used for bootloader
type and version. This has generally worked without *too* much pain,
but we're getting close to flat running out of ID fields.
Add extension fields for both type and version. The type will be
extended if it the old field is 0xE; the version is a simple MSB
extension.
Keep /proc/sys/kernel/bootloader_type containing
(type << 4) + (ver & 0xf) for backwards compatiblity, but also add
/proc/sys/kernel/bootloader_version which contains the full version
number.
[ Impact: new feature to support more bootloaders ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Update CONFIG_RELOCATABLE, CONFIG_PHYSICAL_START and
CONFIG_PHYSICAL_ALIGN to reflect the current defaults.
[ Impact: make defconfig match Kconfig defaults ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Update defconfigs to reflect current configuration files. No other
changes.
[ Impact: updates defconfigs to match what "make defconfig" generates ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Remove the EXPERIMENTAL tag from CONFIG_RELOCATABLE and make it the
default. Relocatable kernels have been used for a while now, and
should now have identical semantics to non-relocatable kernels when
loaded by a non-relocating bootloader.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Default CONFIG_PHYSICAL_START and CONFIG_PHYSICAL_ALIGN each to 16 MB,
so that both non-relocatable and relocatable kernels are loaded at
16 MB by a non-relocating bootloader. This is somewhat hacky, but it
appears to be the only way to do this that does not break some some
set of existing bootloaders.
We want to avoid the bottom 16 MB because of large page breakup,
memory holes, and ZONE_DMA. Embedded systems may need to reduce this,
or update their bootloaders to be aware of the new min_alignment field.
[ Impact: performance improvement, avoids problems on some systems ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Document the new bzImage fields for kernel memory placement.
[ Impact: adds documentation ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Make the kernel_alignment field adjustable; this allows us to set it
to a large value (intended to be 16 MB to avoid ZONE_DMA contention,
memory holes and other weirdness) while a smart bootloader can still
force a loading at a lesser alignment if absolutely necessary.
Also export pref_address (preferred loading address, corresponding to
the link-time address) and init_size, the total amount of linear
memory the kernel will require during initialization.
[ Impact: allows better kernel placement, gives bootloader more info ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Remove a couple of lines of dead code from
arch/x86/boot/compressed/head_*.S; all of these update registers that
are dead in the current code.
[ Impact: cleanup ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Use LOAD_PHYSICAL_ADDR instead of CONFIG_PHYSICAL_START in the 64-bit
decompression code, for equivalence with the 32-bit code.
[ Impact: cleanup, increases code similarity ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Make symbols from the main vmlinux, as opposed to just
compressed/vmlinux, available to header.S. Also, export a few
additional symbols.
This will be used in a subsequent patch to export the total memory
footprint of the kernel.
[ Impact: enable future enhancement ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Determine the compressed code offset (from the kernel runtime address)
at compile time. This allows some minor optimizations in
arch/x86/boot/compressed/head_*.S, but more importantly it makes this
value available to the build process, which will enable a future patch
to export the necessary linear memory footprint into the bzImage
header.
[ Impact: cleanup, future patch enabling ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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In the pre-decompression code, use the appropriate largest possible
rep movs and rep stos to move code and clear bss, respectively. For
reverse copy, do note that the initial values are supposed to be the
address of the first (highest) copy datum, not one byte beyond the end
of the buffer.
rep strings are not necessarily the fastest way to perform these
operations on all current processors, but are likely to be in the
future, and perhaps more importantly, we want to encourage the
architecturally right thing to do here.
This also fixes a couple of trivial inefficiencies on 64 bits.
[ Impact: trivial performance enhancement, increase code similarity ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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The 64-bit code already clears EFLAGS as soon as it has a stack. This
seems like a reasonable precaution, so do it on 32 bits as well.
[ Impact: extra paranoia ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Set up the decompression stack as soon as we know where it needs to
go. That way we have a full-service stack as soon as possible, rather
than relying on the BP_scratch field.
Note that the stack does need to be empty during bss zeroing (or
else the stack needs to be moved out of the bss segment, which is also
an option.)
[ Impact: cleanup, minor paranoia ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Both on 32 and 64 bits, we copy all the way up to the end of bss,
except that on 64 bits there is a hack to avoid copying on top of the
page tables. There is no point in copying bss at all, especially
since we are just about to zero it all anyway.
To clean up and unify the handling, we now do:
- copy from startup_32 to _bss.
- zero from _bss to _ebss.
- the _ebss symbol is aligned to an 8-byte boundary.
- the page tables are moved to a separate section.
Use _bss as the copy endpoint since _edata may be misaligned.
[ Impact: cleanup, trivial performance improvement ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Clean up style issues in arch/x86/boot/compressed/head_64.S. This
file had a lot fewer style issues than its 32-bit cousin, but the ones
it has are worth fixing, especially since it makes the two files more
similar.
[ Impact: cleanup, no object code change ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Reformat arch/x86/boot/compressed/head_32.S to be closer to currently
preferred kernel assembly style, that is:
- opcode and operand separated by tab
- operands separated by ", "
- C-style comments
This also makes it more similar to head_64.S.
[ Impact: cleanup, no object code change ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Use the BP_scratch symbol from asm-offsets.h instead of hard-coding
the location.
[ Impact: cleanup ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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When generating the compression suffix in
arch/x86/boot/compressed/Makefile, follow standard Kbuild
conventions, that is:
- Use a dash not underscore before y/m/n endings
- Use := whenever possible.
Requested-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Simplify the arch/x86/boot/compressed/Makefile, by using the new
capability of specifying multiple inputs to a compressor, and the
CONFIG_X86_NEED_RELOCS Kconfig symbol.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
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We only need to build relocations when we are building a 32-bit
relocatable kernel. Rather than unnecessarily complicating the
Makefiles, make an explicit Kbuild symbol for this.
[ Impact: permits future cleanup ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
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Allow the compression commands in Kbuild (i.e. gzip, bzip2, lzma) to
take multiple input files and emit the concatenated compressed
output. This avoids an intermediate step when a kernel image is built
from multiple components, such as the relocatable x86-32 kernel.
Sam Ravnborg integrated the bin_size script into the Makefile.
[ Impact: new build feature, not yet used ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
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Aligning the .bss section makes it trivial to use large operation
sizes for moving the initialized sections and clearing the .bss.
The alignment chosen (L1 cache) is somewhat arbitrary, but should be
large enough to avoid all known performance traps and small enough to
not cause troubles.
[ Impact: trivial performance enhancement, future patch prep ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Jesper reported that he saw following build issue:
> ld:arch/x86/boot/compressed/vmlinux.lds:9: syntax error
> make[2]: *** [arch/x86/boot/compressed/vmlinux] Error 1
> make[1]: *** [arch/x86/boot/compressed/vmlinux] Error 2
> make: *** [bzImage] Error 2
CPP defines the symbol "i386" to "1".
Undefine this to fix it.
[ Impact: build fix with certain tool chains ]
Reported-by: Jesper Dangaard Brouer <jdb@comx.dk>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <alpine.LFD.2.00.0904260958190.3101@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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__init_begin/_end symbols should be inside sections as well,
otherwise the relocatable kernel gets confused when freeing
init sections in the wrong place.
[ Impact: fix bootup crash ]
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20090429105056.GA28720@uranus.ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Acked-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-2-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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32 bit:
- explicit page align .bss
- move ALING() out of .brk output section
- discard *(.eh_frame)
64 bit:
- move ALIGN() out of .bss output section
- move ALIGN() out of .brk output section
- use a dedicated section to define _end
[ Impact: unify and fix section alignments in linker script ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-13-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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32 bit:
- move __init_end outside the .bss output section
It really did not belong in there
[ Impact: 64-bit: cleanup, 32-bit: refactor linker script ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-12-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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[ Impact: cleanup ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-11-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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32 bit:
- increase alignment from 4 to 8 for .parainstructions
- increase alignment from 4 to 8 for .altinstructions
64 bit:
- move ALIGN() outside output section for .altinstructions
None of the above should result in any functional change.
[ Impact: refactor and unify linker script ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-10-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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32-bit:
- Move definition of __init_begin outside output_section
because it covers more than one section
- Move ALIGN() for end-of-section inside .smp_locks output section.
Same effect but the intent is better documented that
we need both start and end aligned.
64-bit:
- Move ALIGN() outside output section in .init.setup
- Deleted unused __smp_alt_* symbols
None of the above should result in any functional change.
[ Impact: refactor and unify linker script ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-9-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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[ Impact: cleanup ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-8-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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For 64 bit the following functional changes are introduced:
- .data.page_aligned has moved
- .data.cacheline_aligned has moved
- .data.read_mostly has moved
- ALIGN() moved out of output section for .data.cacheline_aligned
- ALIGN() moved out of output section for .data.page_aligned
Notice that 32 bit and 64 bit has different location of _edata.
.data_nosave is 32 bit only as 64 bit is special due to PERCPU.
[ Impact: 32-bit: cleanup, 64-bit: use 32-bit linker script ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-7-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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[ Impact: cleanup ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-6-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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32 bit x86 had a dedicated .text.head output section,
whereas 64 bit had it all in a single output section.
In the unified version the dedicated .text.head output section
was kept to have full control over the head code.
32 bit:
- Moved definition of _stext to the linker script.
The definition is located _after_ .text.page_aligned as this
is what 32 bit did before.
The ALIGN(8) was introduced so we hit the exact same address
(on the tested config) before and after the move.
I assume that it is a bug that _stext did not cover the
.text.page_aligned section - if this is true it can be fixed
in a follow-up patch (and the ugly ALIGN() can be dropped).
[ Impact: 64-bit: cleanup, 32-bit: use the 64-bit linker script ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-5-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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[ Impact: cleanup ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-4-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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PHDRS are not equal for the two - so
use ifdefs to cover up for that.
On the assumption that they may become equal the ifdef
is inside the PHDRS definiton.
[ Impact: cleanup ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-3-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Merge everything except PHDRS and SECTIONS into
vmlinux.lds.S.
[ Impact: cleanup ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-2-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Beautify vmlinux_32.lds.S:
- Use tabs for indent
- Located curly braces like in C code
- Rearranged a few comments
To see actual differences use "git diff -b" which
ignore 'whitespace' changes.
The beautification is done to prepare a unification
of the _32 and _64 variants of the linker scripts.
[ Impact: cleanup ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1240991249-27117-1-git-send-email-sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Look at the:
diff -u arch/x86/boot/compressed/vmlinux_*.lds
output and realize that they're basially exactly the same except for
trivial naming differences, and the fact that the 64-bit version has a
"pgtable" thing.
So unify them.
There's some trivial cleanup there (make the output format a Kconfig thing
rather than doing #ifdef's for it, and unify both 32-bit and 64-bit BSS
end to "_ebss", where 32-bit used to use the traditional "_end"), but
other than that it's really very mindless and straigt conversion.
For example, I think we should aim to remove "startup_32" vs "startup_64",
and just call it "startup", and get rid of one more difference. I didn't
do that.
Also, notice the comment in the unified vmlinux.lds.S talks about
"head_64" and "startup_32" which is an odd and incorrect mix, but that was
actually what the old 64-bit only lds file had, so the confusion isn't
new, and now that mixing is arguably more accurate thanks to the
vmlinux.lds.S file being shared between the two cases ;)
[ Impact: cleanup, unification ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Beautify vmlinux_64.lds.S:
- Use tabs for indent
- Located curly braces like in C code
- Rearranged a few comments
There is no functional changes in this patch
The beautification is done to prepare a unification
of the _32 and the _64 variants of the linker scripts.
[ Impact: cleanup ]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20090426210742.GA3464@uranus.ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Introducing this Kbuild file allow us to:
make arch/x86/
And thus building all the core part of x86.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Jaswinder Singh Rajput <jaswinder@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
ALSA: hda - Fix the cmd cache keys for amp verbs
ALSA: add missing definitions(letters) to HD-Audio.txt
ALSA: hda - Add quirk mask for Fujitsu Amilo laptops with ALC883
[ALSA] intel8x0: add one retry to the ac97_clock measurement routine
[ALSA] intel8x0: fix wrong conditions in ac97_clock measure routine
ALSA: hda - Avoid call of snd_jack_report at release
ALSA: add private_data to struct snd_jack
ALSA: snd-usb-caiaq: rename files to remove redundant information in file pathes
ALSA: snd-usb-caiaq: clean up header includes
ALSA: sound/pci: use memdup_user()
ALSA: sound/usb: use memdup_user()
ALSA: sound/isa: use memdup_user()
ALSA: sound/core: use memdup_user()
[ALSA] intel8x0: do not use zero value from PICB register
[ALSA] intel8x0: an attempt to make ac97_clock measurement more reliable
[ALSA] pcm-midlevel: Add more strict buffer position checks based on jiffies
[ALSA] hda_intel: fix unexpected ring buffer positions
ASoC: Disable S3C64xx support in Kconfig
ASoC: magician: remove un-necessary #include of pxa-regs.h and hardware.h
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* git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-fixes:
GFS2: Use DEFINE_SPINLOCK
GFS2: cleanup file_operations mess
GFS2: Move umount flush rwsem
GFS2: Fix symlink creation race
GFS2: Make quotad's waiting interruptible
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* 'for-linus' of git://git.kernel.dk/linux-2.6-block: (28 commits)
cfq-iosched: add close cooperator code
cfq-iosched: log responsible 'cfqq' in idle timer arm
cfq-iosched: tweak kick logic a bit more
cfq-iosched: no need to save interrupts in cfq_kick_queue()
brd: fix cacheflushing
brd: support barriers
swap: Remove code handling bio_alloc failure with __GFP_WAIT
gfs2: Remove code handling bio_alloc failure with __GFP_WAIT
ext4: Remove code handling bio_alloc failure with __GFP_WAIT
dio: Remove code handling bio_alloc failure with __GFP_WAIT
block: Remove code handling bio_alloc failure with __GFP_WAIT
bio: add documentation to bio_alloc()
splice: add helpers for locking pipe inode
splice: remove generic_file_splice_write_nolock()
ocfs2: fix i_mutex locking in ocfs2_splice_to_file()
splice: fix i_mutex locking in generic_splice_write()
splice: remove i_mutex locking in splice_from_pipe()
splice: split up __splice_from_pipe()
block: fix SG_IO to return a proper error value
cfq-iosched: don't delay queue kick for a merged request
...
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* topic/hda:
ALSA: hda - Fix the cmd cache keys for amp verbs
ALSA: add missing definitions(letters) to HD-Audio.txt
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Fix the key value generation for get/set amp verbs. The upper bits of
the parameter have to be combined with the verb value to be unique for
each direction/index of amp access.
This fixes the resume problem on some hardwares like Macbook after
the channel mode is changed.
Tested-by: Johannes Berg <johannes@sipsolutions.net>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
powerpc: pseries/dtl.c should include asm/firmware.h
powerpc: Fix data-corrupting bug in __futex_atomic_op
powerpc/pseries: Set error_state to pci_channel_io_normal in eeh_report_reset()
powerpc: Allow 256kB pages with SHMEM
powerpc: Document new FSL I2C bindings and cleanup
powerpc/mm: Fix compile warning
powerpc/85xx: TQM8548: update defconfig
powerpc/85xx: TQM8548: use proper phy-handles for enet2 and enet3
powerpc/85xx: TQM85xx: correct address of LM75 I2C device nodes
powerpc: Add support for early tlbilx opcode
powerpc: Fix tlbilx opcode
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It turns out that 'smp_call_function_many()' doesn't work at all like
'smp_call_function_single()', and my change to Andrew's patch to use it
rather than a loop over all CPU's acpi-cpufreq doesn't work.
My bad.
'smp_call_function_many()' has two "features" (aka "documented bugs"):
(a) it needs to be called with preemption disabled, because it uses
smp_processor_id() without guarding the CPU lookup with 'get_cpu()'
and 'put_cpu()' like the 'single' variant does.
(b) even if the current CPU is part of the CPU mask, it won't do the
call on that CPU.
Still, we're better off trying to use 'smp_call_function_many()' than
looping over CPU's, since it at least in theory allows us to use a
broadcast IPI and do it all in parallel. So let's just work around the
silly semantic bugs in that function.
Reported-and-tested-by: Ali Gholami Rudi <ali@rudi.ir>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dave Jones <davej@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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If we have processes that are working in close proximity to each
other on disk, we don't want to idle wait. Instead allow the close
process to issue a request, getting better aggregate bandwidth.
The anticipatory scheduler has similar checks, noop and deadline do
not need it since they don't care about process <-> io mappings.
The code for CFQ is a little more involved though, since we split
request queues into per-process contexts.
This fixes a performance problem with eg dump(8), since it uses
several processes in some silly attempt to speed IO up. Even if
dump(8) isn't really a valid case (it should be fixed by using
CLONE_IO), there are other cases where we see close processes
and where idling ends up hurting performance.
Credit goes to Jeff Moyer <jmoyer@redhat.com> for writing the
initial implementation.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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