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Unlike x86, x86_64 already passes arguments in registers. The use of
regparm attribute makes no difference in produced code, and the use of
fastcall just bloats the code.
Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
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This patch resolves the issue of running with numa=fake=X on kernel command
line on x86_64 machines that have big IO hole. While calculating the size
of each node now we look at the total hole size in that range.
Previously there were nodes that only had IO holes in them causing kernel
boot problems. We now use the NODE_MIN_SIZE (64MB) as the minimum size of
memory that any node must have. We reduce the number of allocated nodes if
the number of nodes specified on kernel command line results in any node
getting memory smaller than NODE_MIN_SIZE.
This change allows the extra memory to be incremented in NODE_MIN_SIZE
granule and uniformly distribute among as many nodes (called big nodes) as
possible.
[akpm@osdl.org: build fix]
Signed-off-by: David Rientjes <reintjes@google.com>
Signed-off-by: Paul Menage <menage@google.com>
Signed-off-by: Rohit Seth <rohitseth@google.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
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It makes more sense to end the stack trace with ULONG_MAX only if
nr_entries < max_entries. Otherwise, we lose one entry in the long stack
traces and cannot know whether the trace was complete or not.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Cc: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
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- add SWIOTLB config help text
- mention Documentation/x86_64/boot-options.txt in
Documentation/kernel-parameters.txt
- remove the duplication of the iommu kernel parameter documentation.
- Better explanation of some of the iommu kernel parameter options.
- "32MB<<order" instead of "32MB^order".
- Mention the default "order" value.
- list the four existing PCI-DMA mapping implementations of arch x86_64
- group the iommu= option keywords by PCI-DMA mapping implementation.
- Distinguish iommu= option keywords from number arguments.
- Explain the meaning of DAC and SAC.
Signed-off-by: Karsten Weiss <knweiss@science-computing.de>
Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Muli Ben-Yehuda <muli@il.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
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Currently, unreachable_devices() compares value of mmconfig and value
of conf1. But it doesn't check the device is reachable or not.
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andi Kleen <ak@suse.de>
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This just cleans up.
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andi Kleen <ak@suse.de>
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MMCONFIG_APER_XXX is unneeded in arch/x86_64/pci/mmconfig.c.
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andi Kleen <ak@suse.de>
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This rejects broken MCFG tables on Asus. When the table
looks bogus just disable mmconfig
Arjan and Andi suggested this.
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andi Kleen <ak@suse.de>
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Current mmconfig has some problems of remapped range.
a) In the case of broken MCFG tables on Asus etc., we need to remap 256M
range, but currently only remap 1M.
b) The base address always corresponds to bus number 0, but currently we
are assuming it corresponds to start bus number.
This patch fixes the above problems.
(akpm: Arjan suggests that if the MCFG table is broken we just shouldn't use
it, rather than try to work around things).
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
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i386 and x86-64 pci mmconfig code have a lot in common. So share what's
shareable between the two.
Signed-off-by: Olivier Galibert <galibert@pobox.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
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- Removed an extraneous debug message from allocate_cachealigned_map
- Changed extract_lsb_from_nodes to return 63 for the case where there was
only one memory node. The prevents the creation of the dynamic hashmap.
- Changed extract_lsb_from_nodes to use only the starting memory address of
a node. On an ES7000, our nodes overlap the starting and ending address,
meaning, that we see nodes like
00000 - 10000
10000 - 20000
But other systems have nodes whose start and end addresses do not overlap.
For example:
00000 - 0FFFF
10000 - 1FFFF
In this case, using the ending address will result in an LSB much lower
than what is possible. In this case an LSB of 1 when in reality it should
be 16.
Cc: Andi Kleen <ak@suse.de>
Cc: Rohit Seth <rohitseth@google.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andi Kleen <ak@suse.de>
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Remove the statically allocated memory to NUMA node hash map in favor of a
dynamically allocated memory to node hash map (it is cache aligned).
This patch has the nice side effect in that it allows the hash map to grow
for systems with large amounts of memory (256GB - 1TB), but suffer from
having small PCI space tacked onto the boot node (which is somewhere
between 192MB to 512MB on the ES7000).
Signed-off-by: Amul Shah <amul.shah@unisys.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Cc: Rohit Seth <rohitseth@google.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
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This does user copies in fs write() into the page cache with write combining.
This pushes the destination out of the CPU's cache, but allows higher bandwidth
in some case.
The theory is that the page cache data is usually not touched by the
CPU again and it's better to not pollute the cache with it. Also it is a little
faster.
Signed-off-by: Andi Kleen <ak@suse.de>
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Signed-off-by: Andi Kleen <ak@suse.de>
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Many struct file_operations in the kernel can be "const". Marking them const
moves these to the .rodata section, which avoids false sharing with potential
dirty data. In addition it'll catch accidental writes at compile time to
these shared resources.
[akpm@osdl.org: sparc64 fix]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Remove in-source externs, linux/init.h is included in all cases.
This is a fixups for "Dynamic kernel command-line" patch.
It also includes some uml __init fixups so that we can __initdata also its
command_line.
Signed-off-by: Alon Bar-Lev <alon.barlev@gmail.com>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1. Rename saved_command_line into boot_command_line.
2. Set command_line as __initdata.
Signed-off-by: Alon Bar-Lev <alon.barlev@gmail.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Part of long forgotten patch
http://groups.google.com/group/fa.linux.kernel/msg/e98e941ce1cf29f6?dmode=source
Since then, m32r grabbed two copies.
Leave s390 copy because of important absence of CONFIG_VT, but remove
references to non-existent timerlist_lock. ia64 also loses timerlist_lock.
Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Andi Kleen <ak@muc.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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I noticed that almost all architectures implemented exactly the same
sys32_sysinfo... except parisc, where a bug was to be found in handling of
the uptime. So let's remove a whole whack of code for fun and profit.
Cribbed compat_sys_sysinfo from x86_64's implementation, since I figured it
would be the best tested.
This patch incorporates Arnd's suggestion of not using set_fs/get_fs, but
instead extracting out the common code from sys_sysinfo.
Cc: Christoph Hellwig <hch@infradead.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Delete the few remaining unnecessary calls to memset(0) after a call to
kzalloc().
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Adam Belay <ambx1@neo.rr.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Replace appropriate pairs of "kmem_cache_alloc()" + "memset(0)" with the
corresponding "kmem_cache_zalloc()" call.
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Roland McGrath <roland@redhat.com>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: Greg KH <greg@kroah.com>
Acked-by: Joel Becker <Joel.Becker@oracle.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Jan Kara <jack@ucw.cz>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: James Morris <jmorris@namei.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Update all arch/*/kernel/vmlinux.lds.S to not include space for initramfs
when CONFIG_BLK_DEV_INITRAMFS is not selected. This saves another 4 kbytes
on most platfoms (some reserve PAGE_SIZE for initramfs).
Signed-off-by: Jean-Paul Saman <jean-paul.saman@nxp.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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As Andi pointed out: CONFIG_GENERIC_ISA_DMA only disables the ISA DMA
channel management. Other functionality may still expect GFP_DMA to
provide memory below 16M. So we need to make sure that CONFIG_ZONE_DMA is
set independent of CONFIG_GENERIC_ISA_DMA. Undo the modifications to
mm/Kconfig where we made ZONE_DMA dependent on GENERIC_ISA_DMA and set
theses explicitly in each arches Kconfig.
Reviews must occur for each arch in order to determine if ZONE_DMA can be
switched off. It can only be switched off if we know that all devices
supported by a platform are capable of performing DMA transfers to all of
memory (Some arches already support this: uml, avr32, sh sh64, parisc and
IA64/Altix).
In order to switch ZONE_DMA off conditionally, one would have to establish
a scheme by which one can assure that no drivers are enabled that are only
capable of doing I/O to a part of memory, or one needs to provide an
alternate means of performing an allocation from a specific range of memory
(like provided by alloc_pages_range()) and insure that all drivers use that
call. In that case the arches alloc_dma_coherent() may need to be modified
to call alloc_pages_range() instead of relying on GFP_DMA.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This patch uses install_special_mapping for the ia32 vDSO setup, consolidating
duplicated code.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* master.kernel.org:/pub/scm/linux/kernel/git/gregkh/pci-2.6: (41 commits)
Revert "PCI: remove duplicate device id from ata_piix"
msi: Make MSI useable more architectures
msi: Kill the msi_desc array.
msi: Remove attach_msi_entry.
msi: Fix msi_remove_pci_irq_vectors.
msi: Remove msi_lock.
msi: Kill msi_lookup_irq
MSI: Combine pci_(save|restore)_msi/msix_state
MSI: Remove pci_scan_msi_device()
MSI: Replace pci_msi_quirk with calls to pci_no_msi()
PCI: remove duplicate device id from ipr
PCI: remove duplicate device id from ata_piix
PCI: power management: remove noise on non-manageable hw
PCI: cleanup MSI code
PCI: make isa_bridge Alpha-only
PCI: remove quirk_sis_96x_compatible()
PCI: Speed up the Intel SMBus unhiding quirk
PCI Quirk: 1k I/O space IOBL_ADR fix on P64H2
shpchp: delete trailing whitespace
shpchp: remove DBG_XXX_ROUTINE
...
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The arch hooks arch_setup_msi_irq and arch_teardown_msi_irq are now
responsible for allocating and freeing the linux irq in addition to
setting up the the linux irq to work with the interrupt.
arch_setup_msi_irq now takes a pci_device and a msi_desc and returns
an irq.
With this change in place this code should be useable by all platforms
except those that won't let the OS touch the hardware like ppc RTAS.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6: (140 commits)
ACPICA: reduce table header messages to fit within 80 columns
asus-laptop: merge with ACPICA table update
ACPI: bay: Convert ACPI Bay driver to be compatible with sysfs update.
ACPI: bay: new driver is EXPERIMENTAL
ACPI: bay: make drive_bays static
ACPI: bay: make bay a platform driver
ACPI: bay: remove prototype procfs code
ACPI: bay: delete unused variable
ACPI: bay: new driver adding removable drive bay support
ACPI: dock: check if parent is on dock
ACPICA: fix gcc build warnings
Altix: Add ACPI SSDT PCI device support (hotplug)
Altix: ACPI SSDT PCI device support
ACPICA: reduce conflicts with Altix patch series
ACPI_NUMA: fix HP IA64 simulator issue with extended memory domain
ACPI: fix HP RX2600 IA64 boot
ACPI: build fix for IBM x440 - CONFIG_X86_SUMMIT
ACPICA: Update version to 20070126
ACPICA: Fix for incorrect parameter passed to AcpiTbDeleteTable during table load.
ACPICA: Update copyright to 2007.
...
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- add proper __init decoration to swiotlb's init code (and the code calling
it, where not already the case)
- replace uses of 'unsigned long' with dma_addr_t where appropriate
- do miscellaneous simplicfication and cleanup
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
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Signed-off-by: Len Brown <len.brown@intel.com>
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Signed-off-by: Len Brown <len.brown@intel.com>
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Signed-off-by: Len Brown <len.brown@intel.com>
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This patch makes x86_64 define arch_vma_name for CONFIG_IA32_EMULATION. This
makes the ia32 vDSO mapping appear in /proc/PID/maps with "[vdso]" for ia32
processes, as it does on native i386.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This patch fixes ia32 core dumps on x86_64 to include just one phdr for the
vDSO vma. Currently it writes a confused format with two phdrs for the
address, one without contents and one with. This patch removes the
special-case core writing macros for the ia32 vDSO. Instead, it uses
VM_ALWAYSDUMP in the vma. This changes core dumps so they no longer include
the non-PT_LOAD phdrs from the vDSO, consistent with fixed native i386 core
dumps.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Commit f2802e7f571c05f9a901b1f5bd144aa730ccc88e and its x86 version
(b7471c6da94d30d3deadc55986cc38d1ff57f9ca) adds nmi_known_cpu() check
while parsing boot options in x86_64 and i386.
With that, "nmi_watchdog=2" stops working for me on Intel Core 2 CPU
based system.
The problem is, setup_nmi_watchdog is called while parsing the boot
option and identify_cpu is not done yet. So, the return value of
nmi_known_cpu() is not valid at this point.
So revert that check. This should not have any adverse effect as the
nmi_known_cpu() check is done again later in enable_lapic_nmi_watchdog().
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix
linux/arch/x86_64/ia32/ia32_aout.c: In function ‘create_aout_tables’:
linux/arch/x86_64/ia32/ia32_aout.c:244: warning: cast from pointer to integer of different size
linux/arch/x86_64/ia32/ia32_aout.c:253: warning: cast from pointer to integer of different size
with gcc 4.3
Signed-off-by: Andi Kleen <ak@suse.de>
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Signed-off-by: Muli Ben-Yehuda <muli@il.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
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Ensure that no SMI interrupts occur between the read of the HPET & TSC
in the clock calibration loop.
I noticed that a 2.66GHz system incorrectly detected the processor
clock speed about 1/7 of the time:
time.c: Detected 2660.005 MHz processor. (most of the time)
time.c: Detected 2988.203 MHz processor. (sometime)
The problem is caused by an SMI interrupt occuring in hpet_calibrate_tsc()
between the read of the HPET & TSC. Prior to switching the BIOS into
ACPI mode, it appears that every 27msec an SMI interrupt occurs. The
SMI interrupt takes 4.8 msec to process.
Note: On my test system, TICK_MIN had to be >380. I picked 5000
to minimize risk of having a value that is too small for other
platforms.
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Andi Kleen <ak@suse.de>
arch/x86_64/kernel/time.c | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)
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Signed-off-by: Andi Kleen <ak@suse.de>
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This reverts commit b026872601976f666bae77b609dc490d1834bf77, which has
been linked to several problem reports with IO-APIC and the timer.
Machines either don't boot because the timer doesn't happen, or we get
double timer interrupts because we end up double-routing the timer irq
through multiple interfaces.
See for example
http://lkml.org/lkml/2006/12/16/101
http://lkml.org/lkml/2007/1/3/9
http://bugzilla.kernel.org/show_bug.cgi?id=7789
about some of the discussion.
Patches to fix this cleanup exist (and have been confirmed to work fine
at least for some of the affected cases) and we'll revisit it for
2.6.21, but this late in the -rc series we're better off just reverting
the incomplete commit that caused the problems.
Suggested-by: Adrian Bunk <bunk@stusta.de>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Yinghai Lu <yinghai.lu@amd.com>
Cc: Andrew Morton <akpm@osdl.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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* master.kernel.org:/pub/scm/linux/kernel/git/davej/cpufreq:
[CPUFREQ] longhaul: Kill off warnings introduced by recent changes.
[CPUFREQ] Uninitialized use of cmd.val in arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c:acpi_cpufreq_target()
[CPUFREQ] Longhaul - Always guess FSB
[CPUFREQ] Longhaul - Fix up powersaver assumptions.
[CPUFREQ] longhaul: Fix up unreachable code.
[CPUFREQ] speedstep-centrino: missing space and bracket
[CPUFREQ] Bug fix for acpi-cpufreq and cpufreq_stats oops on frequency change notification
[CPUFREQ] select consistently
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If caller passed the tsk, we should use it to validate a stack ptr.
Otherwise, sysrq-t and other debugging stuff doesn't work.
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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CALGARY_IOMMU_ENABLED_BY_DEFAULT"
This reverts commit a9622f6219ce58faba1417743bf3078501eb3434. Now that
the Calgary code apparently detects itself properly, it's not needed any
more.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The apple fn keys don't work anymore with 2.6.20-rc1.
The reason is that USB_HID_POWERBOOK appears in several files although
USB_HIDINPUT_POWERBOOK is the thing to be used.
The patch fixes this.
Cc: Greg KH <greg@kroah.com>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Make x86_64 ACPI_CPU_FREQ select CPU_FREQ_TABLE like other methods do.
(although we should still eliminate as much use of 'select' as possible)
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dave Jones <davej@redhat.com>
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APM idle code
Fernando Lopez-Lezcano reported frequent scheduling latencies and audio
xruns starting at the 2.6.18-rt kernel, and those problems persisted all
until current -rt kernels. The latencies were serious and unjustified by
system load, often in the milliseconds range.
After a patient and heroic multi-month effort of Fernando, where he
tested dozens of kernels, tried various configs, boot options,
test-patches of mine and provided latency traces of those incidents, the
following 'smoking gun' trace was captured by him:
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | caller
\ / ||||| \ | /
IRQ_19-1479 1D..1 0us : __trace_start_sched_wakeup (try_to_wake_up)
IRQ_19-1479 1D..1 0us : __trace_start_sched_wakeup <<...>-5856> (37 0)
IRQ_19-1479 1D..1 0us : __trace_start_sched_wakeup (c01262ba 0 0)
IRQ_19-1479 1D..1 0us : resched_task (try_to_wake_up)
IRQ_19-1479 1D..1 0us : __spin_unlock_irqrestore (try_to_wake_up)
...
<idle>-0 1...1 11us!: default_idle (cpu_idle)
...
<idle>-0 0Dn.1 602us : smp_apic_timer_interrupt (c0103baf 1 0)
...
<...>-5856 0D..2 618us : __switch_to (__schedule)
<...>-5856 0D..2 618us : __schedule <<idle>-0> (20 162)
<...>-5856 0D..2 619us : __spin_unlock_irq (__schedule)
<...>-5856 0...1 619us : trace_stop_sched_switched (__schedule)
<...>-5856 0D..1 619us : trace_stop_sched_switched <<...>-5856> (37 0)
what is visible in this trace is that CPU#1 ran try_to_wake_up() for
PID:5856, it placed PID:5856 on CPU#0's runqueue and ran resched_task()
for CPU#0. But it decided to not send an IPI that no CPU - due to
TS_POLLING. But CPU#0 never woke up after its NEED_RESCHED bit was set,
and only rescheduled to PID:5856 upon the next lapic timer IRQ. The
result was a 600+ usecs latency and a missed wakeup!
the bug turned out to be an idle-wakeup bug introduced into the mainline
kernel this summer via an optimization in the x86_64 tree:
commit 495ab9c045e1b0e5c82951b762257fe1c9d81564
Author: Andi Kleen <ak@suse.de>
Date: Mon Jun 26 13:59:11 2006 +0200
[PATCH] i386/x86-64/ia64: Move polling flag into thread_info_status
During some profiling I noticed that default_idle causes a lot of
memory traffic. I think that is caused by the atomic operations
to clear/set the polling flag in thread_info. There is actually
no reason to make this atomic - only the idle thread does it
to itself, other CPUs only read it. So I moved it into ti->status.
the problem is this type of change:
if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
- clear_thread_flag(TIF_POLLING_NRFLAG);
+ current_thread_info()->status &= ~TS_POLLING;
smp_mb__after_clear_bit();
while (!need_resched()) {
local_irq_disable();
this changes clear_thread_flag() to an explicit clearing of TS_POLLING.
clear_thread_flag() is defined as:
clear_bit(flag, &ti->flags);
and clear_bit() is a LOCK-ed atomic instruction on all x86 platforms:
static inline void clear_bit(int nr, volatile unsigned long * addr)
{
__asm__ __volatile__( LOCK_PREFIX
"btrl %1,%0"
hence smp_mb__after_clear_bit() is defined as a simple compile barrier:
#define smp_mb__after_clear_bit() barrier()
but the explicit TS_POLLING clearing introduced by the patch:
+ current_thread_info()->status &= ~TS_POLLING;
is not an atomic op! So the clearing of the TS_POLLING bit is freely
reorderable with the reading of the NEED_RESCHED bit - and both now
reside in different memory addresses.
CPU idle wakeup very much depends on ordered memory ops, the clearing of
the TS_POLLING flag must always be done before we test need_resched()
and hit the idle instruction(s). [Symmetrically, the wakeup code needs
to set NEED_RESCHED before it tests the TS_POLLING flag, so memory
ordering is paramount.]
Fernando's dual-core Athlon64 system has a sufficiently advanced memory
ordering model so that it triggered this scenario very often.
( And it also turned out that the reason why these latencies never
triggered on my testsystems is that i routinely use idle=poll, which
was the only idle variant not affected by this bug. )
The fix is to change the smp_mb__after_clear_bit() to an smp_mb(), to
act as an absolute barrier between the TS_POLLING write and the
NEED_RESCHED read. This affects almost all idling methods (default,
ACPI, APM), on all 3 x86 architectures: i386, x86_64, ia64.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
|
if CONFIG_CALGARY_IOMMU is built into the kernel via
CONFIG_CALGARY_IOMMU_ENABLED_BY_DEFAULT, or is enabled via the
iommu=calgary boot option, then the detect_calgary() function runs to
detect the presence of a Calgary IOMMU.
detect_calgary() first searches the BIOS EBDA area for a "rio_table_hdr"
BIOS table. It has this parsing algorithm for the EBDA:
while (offset) {
...
/* The next offset is stored in the 1st word. 0 means no more */
offset = *((unsigned short *)(ptr + offset));
}
got that? Lets repeat it slowly: we've got a BIOS-supplied data
structure, plus Linux kernel code that will only break out of an
infinite parsing loop once the BIOS gives a zero offset. Ok?
Translation: what an excellent opportunity for BIOS writers to lock up
the Linux boot process in an utterly hard to debug place! Indeed the
BIOS jumped on that opportunity on my box, which has the following EBDA
chaining layout:
384, 65282, 65535, 65535, 65535, 65535, 65535, 65535 ...
see the pattern? So my, definitely non-Calgary system happily locks up
in detect_calgary()!
the patch below fixes the boot hang by trusting the BIOS-supplied data
structure a bit less: the parser always has to make forward progress,
and if it doesnt, we break out of the loop and i get the expected kernel
message:
Calgary: Unable to locate Rio Grande Table in EBDA - bailing!
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Muli Ben-Yehuda <muli@il.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
|
one of my boxes didnt boot the 2.6.20-rc1-rt0 kernel rpm, it hung during
early bootup. After an hour or two of happy debugging i narrowed it down
to the CALGARY_IOMMU_ENABLED_BY_DEFAULT option, which was freshly added
to 2.6.20 via the x86_64 tree and /enabled by default/.
commit bff6547bb6a4e82c399d74e7fba78b12d2f162ed claims:
[PATCH] Calgary: allow compiling Calgary in but not using it by default
This patch makes it possible to compile Calgary in but not use it by
default. In this mode, use 'iommu=calgary' to activate it.
but the change does not actually practice it:
config CALGARY_IOMMU_ENABLED_BY_DEFAULT
bool "Should Calgary be enabled by default?"
default y
depends on CALGARY_IOMMU
help
Should Calgary be enabled by default? if you choose 'y', Calgary
will be used (if it exists). If you choose 'n', Calgary will not be
used even if it exists. If you choose 'n' and would like to use
Calgary anyway, pass 'iommu=calgary' on the kernel command line.
If unsure, say Y.
it's both 'default y', and says "If unsure, say Y". Clearly not a typo.
disabling this option makes my box boot again. The patch below fixes the
Kconfig entry. Grumble.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
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It has caused more problems than it ever really solved, and is
apparently not getting cleaned up and fixed. We can put it back when
it's stable and isn't likely to make warning or bug events worse.
In the meantime, enable frame pointers for more readable stack traces.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
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Conflicts:
drivers/cpufreq/cpufreq.c
|
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Fix typo in 'EXPERIMENTAL' in config CC_STACKPROTECTOR in arch/x86_64/Kconfig.
Signed-off-by: Brice Goglin <brice@myri.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
