1. 26 Sep, 2006 1 commit
  2. 23 Mar, 2006 1 commit
    • Gerd Hoffmann's avatar
      [PATCH] x86: SMP alternatives · 9a0b5817
      Gerd Hoffmann authored
      
      
      Implement SMP alternatives, i.e.  switching at runtime between different
      code versions for UP and SMP.  The code can patch both SMP->UP and UP->SMP.
      The UP->SMP case is useful for CPU hotplug.
      
      With CONFIG_CPU_HOTPLUG enabled the code switches to UP at boot time and
      when the number of CPUs goes down to 1, and switches to SMP when the number
      of CPUs goes up to 2.
      
      Without CONFIG_CPU_HOTPLUG or on non-SMP-capable systems the code is
      patched once at boot time (if needed) and the tables are released
      afterwards.
      
      The changes in detail:
      
        * The current alternatives bits are moved to a separate file,
          the SMP alternatives code is added there.
      
        * The patch adds some new elf sections to the kernel:
          .smp_altinstructions
      	like .altinstructions, also contains a list
      	of alt_instr structs.
          .smp_altinstr_replacement
      	like .altinstr_replacement, but also has some space to
      	save original instruction before replaving it.
          .smp_locks
      	list of pointers to lock prefixes which can be nop'ed
      	out on UP.
          The first two are used to replace more complex instruction
          sequences such as spinlocks and semaphores.  It would be possible
          to deal with the lock prefixes with that as well, but by handling
          them as special case the table sizes become much smaller.
      
       * The sections are page-aligned and padded up to page size, so they
         can be free if they are not needed.
      
       * Splitted the code to release init pages to a separate function and
         use it to release the elf sections if they are unused.
      Signed-off-by: default avatarGerd Hoffmann <kraxel@suse.de>
      Signed-off-by: default avatarChuck Ebbert <76306.1226@compuserve.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      9a0b5817
  3. 11 Jan, 2006 1 commit
  4. 10 Jan, 2006 1 commit
  5. 09 Jan, 2006 2 commits