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Pavel Tatashin fe9af81e52 x86/tsc: Redefine notsc to behave as tsc=unstable 
Currently, the notsc kernel parameter disables the use of the TSC by
sched_clock(). However, this parameter does not prevent the kernel from
accessing tsc in other places.

The only rationale to boot with notsc is to avoid timing discrepancies on
multi-socket systems where TSC are not properly synchronized, and thus
exclude TSC from being used for time keeping. But that prevents using TSC
as sched_clock() as well, which is not necessary as the core sched_clock()
implementation can handle non synchronized TSC based sched clocks just
fine.

However, there is another method to solve the above problem: booting with
tsc=unstable parameter. This parameter allows sched_clock() to use TSC and
just excludes it from timekeeping.

So there is no real reason to keep notsc, but for compatibility reasons the
parameter has to stay. Make it behave like 'tsc=unstable' instead.

[ tglx: Massaged changelog ]

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: steven.sistare@oracle.com
Cc: daniel.m.jordan@oracle.com
Cc: linux@armlinux.org.uk
Cc: schwidefsky@de.ibm.com
Cc: heiko.carstens@de.ibm.com
Cc: john.stultz@linaro.org
Cc: sboyd@codeaurora.org
Cc: hpa@zytor.com
Cc: peterz@infradead.org
Cc: prarit@redhat.com
Cc: feng.tang@intel.com
Cc: pmladek@suse.com
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: linux-s390@vger.kernel.org
Cc: boris.ostrovsky@oracle.com
Cc: jgross@suse.com
Cc: pbonzini@redhat.com
Link: https://lkml.kernel.org/r/20180719205545.16512-12-pasha.tatashin@oracle.com
2018-07-20 00:02:39 +02:00
..
i386 doc: spelling error changes 2014-05-05 15:32:05 +02:00
x86_64 x86/tsc: Redefine notsc to behave as tsc=unstable 2018-07-20 00:02:39 +02:00
00-INDEX Documentation: Fix early-microcode.txt references after file rename 2018-03-27 09:51:23 +02:00
amd-memory-encryption.txt Documentation/x86: Add AMD Secure Encrypted Virtualization (SEV) description 2017-11-07 15:35:54 +01:00
boot.txt docs: fix locations of several documents that got moved 2016-10-24 08:12:35 -02:00
earlyprintk.txt doc: spelling error changes 2014-05-05 15:32:05 +02:00
entry_64.txt x86/asm/entry/64: Update path names 2015-07-02 11:08:50 +02:00
exception-tables.txt x86/mm: Expand the exception table logic to allow new handling options 2016-02-18 09:21:46 +01:00
intel_mpx.txt x86/Documentation: Fix various typos in Documentation/x86/ files 2016-07-01 10:00:10 +02:00
intel_rdt_ui.txt x86/intel_rdt/mba_sc: Documentation for MBA software controller(mba_sc) 2018-05-19 13:16:42 +02:00
kernel-stacks Documentation/x86: Rename IRQSTACKSIZE to IRQ_STACK_SIZE 2015-08-24 11:42:41 -06:00
microcode.txt firmware: Fix up docs referring to FIRMWARE_IN_KERNEL 2018-01-25 12:46:30 +01:00
mtrr.txt x86/mm/mtrr: Remove kernel internal MTRR interfaces: unexport mtrr_add() and mtrr_del() 2015-08-28 10:09:28 +02:00
orc-unwinder.txt x86/unwind: Rename unwinder config options to 'CONFIG_UNWINDER_*' 2017-10-14 10:12:12 +02:00
pat.txt x86/pat: Document the PAT initialization sequence 2016-03-29 12:23:27 +02:00
protection-keys.txt x86/pkeys: Update documentation about availability 2017-11-21 09:34:52 +01:00
pti.txt x86/pti: Document fix wrong index 2018-01-19 16:31:29 +01:00
tlb.txt x86/Documentation: Fix various typos in Documentation/x86/ files 2016-07-01 10:00:10 +02:00
topology.txt x86/topology: Fix function name in documentation 2018-02-23 08:40:12 +01:00
usb-legacy-support.txt
zero-page.txt Merge branch 'linus' into WIP.x86/boot, to fix up conflicts and to pick up updates 2017-03-01 09:02:26 +01:00