SMP support for XLR processors.

[M. Warner Losh]

In message: <l2tdffe84831004201436nf3e9fb18q652ccb3142e5e4f7 at mail.gmail.com>
            Neel Natu <neelnatu at gmail.com> writes:
: Hi JC,
: 
: On Sat, Apr 17, 2010 at 3:40 PM, C. Jayachandran
: <c.jayachandran at gmail.com> wrote:
: > I've a set of initial patches to enable SMP for RMI processors. It
: > comes up in multi-user with 32 CPUs.  I could do buildworld before I
: > updated to HEAD - with head there is a hang during buildworld which
: > I'm looking at, but I think the initial work can be checked in.
: >
: > Neel, can you have a look at the first two patches - one is to enable
: > ULE scheduler and the second one is to move platform_init_ap to
: > slightly later in the initialization sequence.
: >
: > The patches are :
: > 1. mips-ule-support.patch
: > - Enable ULE scheduler for MIPS
: >
: > 2. mips-smp-move-platform.patch
: > - We need a hook to setup message ring and its interrupts, we use
: > platform_init_ap now, and move it be called later for XLR
: >
: 
: I would like to see us move away from #ifdef TARGET_FOO in files under
: mips/mips as much as possible. I think that is achieved easily in this
: instance.
: 
: How about we create a function platform_ap_enable_interrupts() that is
: called from smp_init_secondary()? This function will be defined for
: each platform.
: 
: In the common case this function will simply call
: mips_ap_enable_interrupts() that encapsulates the logic that we
: currently have to setup interrupt masks for clock and ipi interrupts
: in the status register. In the XLR case however it can do something
: different.
: 
: Ditto about the #ifdef TARGET_XLR_XLS in mpboot.S. You can simply have
: an empty platform_init_ap() for XLR.

In general, I'd love to see the TARGET_xxx stuff die entirely in the
mips tree.  That's a hack inherited from the Octeon port.  There's
other mechanisms that are better suited for this stuff...

Warner

: best
: Neel
: 
: > 3. rmi-prid.patch
: > Add RMI processor ID prints - right now it prints unknown processor.
: >
: > 4. rmi-pcib-fix.patch
: > XLR pci bridge should be off the IODI bus, currently it is off the
: > nexus bus which will cause issue when bus_setup_intr on nexus is
: > called
: >
: > 5. cleanup-reorg-cpuid-rge-kx.patch
: > This set has a many changes rolled up:
: >  - clean up rge driver, remove unused code paths and commented code
: > (long way to go still)
: >  - xlr_cpu_id(), xlr_core_id() and xlr_thr_id() updated and usage updated
: >  - fix a bug - we cannot use MIPS_PHYS_TO_KSEG0 on physical addresses
: > here, I have made changes for using XKPHYS to do the same process.
: >  - the KX bit is enabled and interrupts are disabled before the
: > physical memory is read, to avoid the KX bit setting from affecting
: > other code.
: > - move message ring code to on_chip.c from xlr_machdep.c, now all
: > message ring code is in on_chip.c
: >
: > 6. rmi-xlr-smp.patch
: > SMP Support for XLR
: > - mpwait.S added to get the other CPUs out of bootloader code at startup.
: > - SMP platform related functions.
: > - disable shared TLB code for SMP - since threads have different mappings.
: >
: > The patches are also available at
: > http://sites.google.com/site/cjayachandran/files
: >
: > Enabling all 32 threads will need a minor fix in the SMP code, see the
: > patch subr_smp-fix.patch at the same place.
: >
: > Regards,
: > JC.
: >
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