• Hugh Dickins's avatar
    x86: fix HT cpu booting on 32-bit · 5f464707
    Hugh Dickins authored
    Since recent smpboot 32/64-bit merge, my dual Xeon with HT has been
    booting only 2 of its 4 cpus (when running an i386 kernel; but x86_64
    is okay).  J.A. Magallón reports the same.
    
     native_cpu_up: bad cpu 2
     native_cpu_up: bad cpu 3
    
    The mach-default cpu_present_to_apicid() was just returning cpu number
    (2, 3) instead of apicid (6, 7): looks like we now need the x86_64 code
    even for the i386 case.
    
    Comparing with other versions of cpu_present_to_apicid(), it seems a
    good idea to include an NR_CPUS test too, since cpu_present() doesn't
    include that; but that wasn't a problem here, and may no problem at all.
    
    Prior to that smpboot merge, my Xeon booted the two HT siblings on one
    physical first, then the two siblings on the other physical after - when
    i386, but alternated them when x86_64.  Since the merge, the x86_64
    sequence is unchanged, but the i386 sequence is now like x86_64.
    
    I prefer this consistency, and I prefer the new sequence: booting with
    maxcpus=2 then uses the independent physicals without HT sharing.
    Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    5f464707
mach_apic.h 3.11 KB