Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

etire the cpumask_t type and replace it with cpuset_t usage.

This is intended to fix the bug where cpu mask objects are
capped to 32. MAXCPU, then, can now arbitrarely bumped to whatever
value. Anyway, as long as several structures in the kernel are
statically allocated and sized as MAXCPU, it is suggested to keep it
as low as possible for the time being.

Technical notes on this commit itself:
- More functions to handle with cpuset_t objects are introduced.
The most notable are cpusetobj_ffs() (which calculates a ffs(3)
for a cpuset_t object), cpusetobj_strprint() (which prepares a string
representing a cpuset_t object) and cpusetobj_strscan() (which
creates a valid cpuset_t starting from a string representation).
- pc_cpumask and pc_other_cpus are target to be removed soon.
With the moving from cpumask_t to cpuset_t they are now inefficient
and not really useful. Anyway, for the time being, please note that
access to pcpu datas is protected by sched_pin() in order to avoid
migrating the CPU while reading more than one (possible) word
- Please note that size of cpuset_t objects may differ between kernel
and userland. While this is not directly related to the patch itself,
it is good to understand that concept and possibly use the patch
as a reference on how to deal with cpuset_t objects in userland, when
accessing kernland members.
- KTR_CPUMASK is changed and now is represented through a string, to be
set as the example reported in NOTES.

Please additively note that no MAXCPU is bumped in this patch, but
private testing has been done until to MAXCPU=128 on a real 8x8x2(htt)
machine (amd64).

Please note that the FreeBSD version is not yet bumped because of
the upcoming pcpu changes. However, note that this patch is not
targeted for MFC.

People to thank for the time spent on this patch:
- sbruno, pluknet and Nicholas Esborn (nick AT desert DOT net) tested
several revision of the patches and really helped in improving
stability of this work.
- marius fixed several bugs in the sparc64 implementation and reviewed
patches related to ktr.
- jeff and jhb discussed the basic approach followed.
- kib and marcel made targeted review on some specific part of the
patch.
- marius, art, nwhitehorn and andreast reviewed MD specific part of
the patch.
- marius, andreast, gonzo, nwhitehorn and jceel tested MD specific
implementations of the patch.
- Other people have made contributions on other patches that have been
already committed and have been listed separately.

Companies that should be mentioned for having participated at several
degrees:
- Yahoo! for having offered the machines used for testing on big
count of CPUs.
- The FreeBSD Foundation for having sponsored my devsummit attendance,
which has been instrumental.
- Sandvine for having offered offices and infrastructure during
development.

(I really hope I didn't forget anyone, if it happened I apologize in
advance).

Allow the platform code to return a bitmask of running cores rather than just
a number of cores, this allows for a sparse set of CPUs. Implement support
for sparse core masks on Octeon.

XXX jeff@ suggests that all_cpus should include cores that are offline or
running other applications/OSes, so the platform API should be further
extended to allow us to set all_cpus to include all cores that are
physically-present as opposed to only those that are running FreeBSD.

Submitted by: Bhanu Prakash (with modifications)
Reviewed by: jchandra
Glanced at by: kib, jeff, jhb

Use a signed integer to hold the address of a register.

This does the right thing by sign extending the address when compiling for
the n64 abi.

Replace sb_store64()/sb_load64() with mips3_sd()/mips3_ld() respectively.

Obtained from NetBSD.

Suggested by: jmallett@

Sibyte provides a 64-bit read-only counter that counts at half the processor
frequency. This counter can be accessed coherently from both cores.

Use this as the preferred timecounter for the SWARM kernels.

The CP0 COUNT register is unusable as the timecounter on SMP platforms because
the COUNT registers on different CPUs are not guaranteed to be in sync.

SMP support for the mips port.

The platform that supports SMP currently is a SWARM with a dual-core Sibyte
processor. The kernel config file to use is SWARM_SMP.

Reviewed by: imp, rrs

Reimplement all functions to access the system control unit in C.

The only reason we need to have the sb_load64() and sb_store64()
functions in assembly is to cheat the compiler and generate the
'ld' and 'sd' instructions which it otherwise will not do when
compiling for a 32-bit architecture. There are some 64-bit
registers in the SCD unit that must be accessed using 64-bit
load and store instructions.

Merge from projects/mips to head by hand:

Copy the files for the sibyte support (except files in sys/conf and
sys/mips/conf). This targets the Broadcom SWARM board (bcm91250) and
the SB-1 core in the BCM1250 SoC. This work was done by Neel Natu.

Add sibyte device support.

Submitted by: Neelkanth Natu