1. 15 10月, 2007 2 次提交
  2. 20 9月, 2007 1 次提交
  3. 01 8月, 2007 2 次提交
  4. 26 7月, 2007 1 次提交
  5. 18 7月, 2007 1 次提交
  6. 17 7月, 2007 4 次提交
  7. 10 7月, 2007 1 次提交
  8. 17 5月, 2007 2 次提交
  9. 11 5月, 2007 5 次提交
    • D
      signal/timer/event: eventfd core · e1ad7468
      Davide Libenzi 提交于
      This is a very simple and light file descriptor, that can be used as event
      wait/dispatch by userspace (both wait and dispatch) and by the kernel
      (dispatch only).  It can be used instead of pipe(2) in all cases where those
      would simply be used to signal events.  Their kernel overhead is much lower
      than pipes, and they do not consume two fds.  When used in the kernel, it can
      offer an fd-bridge to enable, for example, functionalities like KAIO or
      syslets/threadlets to signal to an fd the completion of certain operations.
      But more in general, an eventfd can be used by the kernel to signal readiness,
      in a POSIX poll/select way, of interfaces that would otherwise be incompatible
      with it.  The API is:
      
      int eventfd(unsigned int count);
      
      The eventfd API accepts an initial "count" parameter, and returns an eventfd
      fd.  It supports poll(2) (POLLIN, POLLOUT, POLLERR), read(2) and write(2).
      
      The POLLIN flag is raised when the internal counter is greater than zero.
      
      The POLLOUT flag is raised when at least a value of "1" can be written to the
      internal counter.
      
      The POLLERR flag is raised when an overflow in the counter value is detected.
      
      The write(2) operation can never overflow the counter, since it blocks (unless
      O_NONBLOCK is set, in which case -EAGAIN is returned).
      
      But the eventfd_signal() function can do it, since it's supposed to not sleep
      during its operation.
      
      The read(2) function reads the __u64 counter value, and reset the internal
      value to zero.  If the value read is equal to (__u64) -1, an overflow happened
      on the internal counter (due to 2^64 eventfd_signal() posts that has never
      been retired - unlickely, but possible).
      
      The write(2) call writes an __u64 count value, and adds it to the current
      counter.  The eventfd fd supports O_NONBLOCK also.
      
      On the kernel side, we have:
      
      struct file *eventfd_fget(int fd);
      int eventfd_signal(struct file *file, unsigned int n);
      
      The eventfd_fget() should be called to get a struct file* from an eventfd fd
      (this is an fget() + check of f_op being an eventfd fops pointer).
      
      The kernel can then call eventfd_signal() every time it wants to post an event
      to userspace.  The eventfd_signal() function can be called from any context.
      An eventfd() simple test and bench is available here:
      
      http://www.xmailserver.org/eventfd-bench.c
      
      This is the eventfd-based version of pipetest-4 (pipe(2) based):
      
      http://www.xmailserver.org/pipetest-4.c
      
      Not that performance matters much in the eventfd case, but eventfd-bench
      shows almost as double as performance than pipetest-4.
      
      [akpm@linux-foundation.org: fix i386 build]
      [akpm@linux-foundation.org: add sys_eventfd to sys_ni.c]
      Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      e1ad7468
    • D
      signal/timer/event: timerfd core · b215e283
      Davide Libenzi 提交于
      This patch introduces a new system call for timers events delivered though
      file descriptors.  This allows timer event to be used with standard POSIX
      poll(2), select(2) and read(2).  As a consequence of supporting the Linux
      f_op->poll subsystem, they can be used with epoll(2) too.
      
      The system call is defined as:
      
      int timerfd(int ufd, int clockid, int flags, const struct itimerspec *utmr);
      
      The "ufd" parameter allows for re-use (re-programming) of an existing timerfd
      w/out going through the close/open cycle (same as signalfd).  If "ufd" is -1,
      s new file descriptor will be created, otherwise the existing "ufd" will be
      re-programmed.
      
      The "clockid" parameter is either CLOCK_MONOTONIC or CLOCK_REALTIME.  The time
      specified in the "utmr->it_value" parameter is the expiry time for the timer.
      
      If the TFD_TIMER_ABSTIME flag is set in "flags", this is an absolute time,
      otherwise it's a relative time.
      
      If the time specified in the "utmr->it_interval" is not zero (.tv_sec == 0,
      tv_nsec == 0), this is the period at which the following ticks should be
      generated.
      
      The "utmr->it_interval" should be set to zero if only one tick is requested.
      Setting the "utmr->it_value" to zero will disable the timer, or will create a
      timerfd without the timer enabled.
      
      The function returns the new (or same, in case "ufd" is a valid timerfd
      descriptor) file, or -1 in case of error.
      
      As stated before, the timerfd file descriptor supports poll(2), select(2) and
      epoll(2).  When a timer event happened on the timerfd, a POLLIN mask will be
      returned.
      
      The read(2) call can be used, and it will return a u32 variable holding the
      number of "ticks" that happened on the interface since the last call to
      read(2).  The read(2) call supportes the O_NONBLOCK flag too, and EAGAIN will
      be returned if no ticks happened.
      
      A quick test program, shows timerfd working correctly on my amd64 box:
      
      http://www.xmailserver.org/timerfd-test.c
      
      [akpm@linux-foundation.org: add sys_timerfd to sys_ni.c]
      Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b215e283
    • D
      signal/timer/event: signalfd core · fba2afaa
      Davide Libenzi 提交于
      This patch series implements the new signalfd() system call.
      
      I took part of the original Linus code (and you know how badly it can be
      broken :), and I added even more breakage ;) Signals are fetched from the same
      signal queue used by the process, so signalfd will compete with standard
      kernel delivery in dequeue_signal().  If you want to reliably fetch signals on
      the signalfd file, you need to block them with sigprocmask(SIG_BLOCK).  This
      seems to be working fine on my Dual Opteron machine.  I made a quick test
      program for it:
      
      http://www.xmailserver.org/signafd-test.c
      
      The signalfd() system call implements signal delivery into a file descriptor
      receiver.  The signalfd file descriptor if created with the following API:
      
      int signalfd(int ufd, const sigset_t *mask, size_t masksize);
      
      The "ufd" parameter allows to change an existing signalfd sigmask, w/out going
      to close/create cycle (Linus idea).  Use "ufd" == -1 if you want a brand new
      signalfd file.
      
      The "mask" allows to specify the signal mask of signals that we are interested
      in.  The "masksize" parameter is the size of "mask".
      
      The signalfd fd supports the poll(2) and read(2) system calls.  The poll(2)
      will return POLLIN when signals are available to be dequeued.  As a direct
      consequence of supporting the Linux poll subsystem, the signalfd fd can use
      used together with epoll(2) too.
      
      The read(2) system call will return a "struct signalfd_siginfo" structure in
      the userspace supplied buffer.  The return value is the number of bytes copied
      in the supplied buffer, or -1 in case of error.  The read(2) call can also
      return 0, in case the sighand structure to which the signalfd was attached,
      has been orphaned.  The O_NONBLOCK flag is also supported, and read(2) will
      return -EAGAIN in case no signal is available.
      
      If the size of the buffer passed to read(2) is lower than sizeof(struct
      signalfd_siginfo), -EINVAL is returned.  A read from the signalfd can also
      return -ERESTARTSYS in case a signal hits the process.  The format of the
      struct signalfd_siginfo is, and the valid fields depends of the (->code &
      __SI_MASK) value, in the same way a struct siginfo would:
      
      struct signalfd_siginfo {
      	__u32 signo;	/* si_signo */
      	__s32 err;	/* si_errno */
      	__s32 code;	/* si_code */
      	__u32 pid;	/* si_pid */
      	__u32 uid;	/* si_uid */
      	__s32 fd;	/* si_fd */
      	__u32 tid;	/* si_fd */
      	__u32 band;	/* si_band */
      	__u32 overrun;	/* si_overrun */
      	__u32 trapno;	/* si_trapno */
      	__s32 status;	/* si_status */
      	__s32 svint;	/* si_int */
      	__u64 svptr;	/* si_ptr */
      	__u64 utime;	/* si_utime */
      	__u64 stime;	/* si_stime */
      	__u64 addr;	/* si_addr */
      };
      
      [akpm@linux-foundation.org: fix signalfd_copyinfo() on i386]
      Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      fba2afaa
    • D
      signal/timer/event fds: anonymous inode source · 5dc8bf81
      Davide Libenzi 提交于
      This patch add an anonymous inode source, to be used for files that need
      and inode only in order to create a file*. We do not care of having an
      inode for each file, and we do not even care of having different names in
      the associated dentries (dentry names will be same for classes of file*).
      This allow code reuse, and will be used by epoll, signalfd and timerfd
      (and whatever else there'll be).
      Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      5dc8bf81
    • C
      SLUB: SLUB_DEBUG must depend on SLUB · d4751a27
      Christoph Lameter 提交于
      Otherwise people get asked about SLUB_DEBUG even if they have another
      slab allocator enabled.
      Signed-off-by: NChristoph Lameter <clameter@sgi.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d4751a27
  10. 10 5月, 2007 2 次提交
  11. 09 5月, 2007 3 次提交
  12. 08 5月, 2007 2 次提交
    • B
      blackfin architecture · 1394f032
      Bryan Wu 提交于
      This adds support for the Analog Devices Blackfin processor architecture, and
      currently supports the BF533, BF532, BF531, BF537, BF536, BF534, and BF561
      (Dual Core) devices, with a variety of development platforms including those
      avaliable from Analog Devices (BF533-EZKit, BF533-STAMP, BF537-STAMP,
      BF561-EZKIT), and Bluetechnix!  Tinyboards.
      
      The Blackfin architecture was jointly developed by Intel and Analog Devices
      Inc.  (ADI) as the Micro Signal Architecture (MSA) core and introduced it in
      December of 2000.  Since then ADI has put this core into its Blackfin
      processor family of devices.  The Blackfin core has the advantages of a clean,
      orthogonal,RISC-like microprocessor instruction set.  It combines a dual-MAC
      (Multiply/Accumulate), state-of-the-art signal processing engine and
      single-instruction, multiple-data (SIMD) multimedia capabilities into a single
      instruction-set architecture.
      
      The Blackfin architecture, including the instruction set, is described by the
      ADSP-BF53x/BF56x Blackfin Processor Programming Reference
      http://blackfin.uclinux.org/gf/download/frsrelease/29/2549/Blackfin_PRM.pdf
      
      The Blackfin processor is already supported by major releases of gcc, and
      there are binary and source rpms/tarballs for many architectures at:
      http://blackfin.uclinux.org/gf/project/toolchain/frs There is complete
      documentation, including "getting started" guides available at:
      http://docs.blackfin.uclinux.org/ which provides links to the sources and
      patches you will need in order to set up a cross-compiling environment for
      bfin-linux-uclibc
      
      This patch, as well as the other patches (toolchain, distribution,
      uClibc) are actively supported by Analog Devices Inc, at:
      http://blackfin.uclinux.org/
      
      We have tested this on LTP, and our test plan (including pass/fails) can
      be found at:
      http://docs.blackfin.uclinux.org/doku.php?id=testing_the_linux_kernel
      
      [m.kozlowski@tuxland.pl: balance parenthesis in blackfin header files]
      Signed-off-by: NBryan Wu <bryan.wu@analog.com>
      Signed-off-by: NMariusz Kozlowski <m.kozlowski@tuxland.pl>
      Signed-off-by: NAubrey Li <aubrey.li@analog.com>
      Signed-off-by: NJie Zhang <jie.zhang@analog.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1394f032
    • C
      SLUB core · 81819f0f
      Christoph Lameter 提交于
      This is a new slab allocator which was motivated by the complexity of the
      existing code in mm/slab.c. It attempts to address a variety of concerns
      with the existing implementation.
      
      A. Management of object queues
      
         A particular concern was the complex management of the numerous object
         queues in SLAB. SLUB has no such queues. Instead we dedicate a slab for
         each allocating CPU and use objects from a slab directly instead of
         queueing them up.
      
      B. Storage overhead of object queues
      
         SLAB Object queues exist per node, per CPU. The alien cache queue even
         has a queue array that contain a queue for each processor on each
         node. For very large systems the number of queues and the number of
         objects that may be caught in those queues grows exponentially. On our
         systems with 1k nodes / processors we have several gigabytes just tied up
         for storing references to objects for those queues  This does not include
         the objects that could be on those queues. One fears that the whole
         memory of the machine could one day be consumed by those queues.
      
      C. SLAB meta data overhead
      
         SLAB has overhead at the beginning of each slab. This means that data
         cannot be naturally aligned at the beginning of a slab block. SLUB keeps
         all meta data in the corresponding page_struct. Objects can be naturally
         aligned in the slab. F.e. a 128 byte object will be aligned at 128 byte
         boundaries and can fit tightly into a 4k page with no bytes left over.
         SLAB cannot do this.
      
      D. SLAB has a complex cache reaper
      
         SLUB does not need a cache reaper for UP systems. On SMP systems
         the per CPU slab may be pushed back into partial list but that
         operation is simple and does not require an iteration over a list
         of objects. SLAB expires per CPU, shared and alien object queues
         during cache reaping which may cause strange hold offs.
      
      E. SLAB has complex NUMA policy layer support
      
         SLUB pushes NUMA policy handling into the page allocator. This means that
         allocation is coarser (SLUB does interleave on a page level) but that
         situation was also present before 2.6.13. SLABs application of
         policies to individual slab objects allocated in SLAB is
         certainly a performance concern due to the frequent references to
         memory policies which may lead a sequence of objects to come from
         one node after another. SLUB will get a slab full of objects
         from one node and then will switch to the next.
      
      F. Reduction of the size of partial slab lists
      
         SLAB has per node partial lists. This means that over time a large
         number of partial slabs may accumulate on those lists. These can
         only be reused if allocator occur on specific nodes. SLUB has a global
         pool of partial slabs and will consume slabs from that pool to
         decrease fragmentation.
      
      G. Tunables
      
         SLAB has sophisticated tuning abilities for each slab cache. One can
         manipulate the queue sizes in detail. However, filling the queues still
         requires the uses of the spin lock to check out slabs. SLUB has a global
         parameter (min_slab_order) for tuning. Increasing the minimum slab
         order can decrease the locking overhead. The bigger the slab order the
         less motions of pages between per CPU and partial lists occur and the
         better SLUB will be scaling.
      
      G. Slab merging
      
         We often have slab caches with similar parameters. SLUB detects those
         on boot up and merges them into the corresponding general caches. This
         leads to more effective memory use. About 50% of all caches can
         be eliminated through slab merging. This will also decrease
         slab fragmentation because partial allocated slabs can be filled
         up again. Slab merging can be switched off by specifying
         slub_nomerge on boot up.
      
         Note that merging can expose heretofore unknown bugs in the kernel
         because corrupted objects may now be placed differently and corrupt
         differing neighboring objects. Enable sanity checks to find those.
      
      H. Diagnostics
      
         The current slab diagnostics are difficult to use and require a
         recompilation of the kernel. SLUB contains debugging code that
         is always available (but is kept out of the hot code paths).
         SLUB diagnostics can be enabled via the "slab_debug" option.
         Parameters can be specified to select a single or a group of
         slab caches for diagnostics. This means that the system is running
         with the usual performance and it is much more likely that
         race conditions can be reproduced.
      
      I. Resiliency
      
         If basic sanity checks are on then SLUB is capable of detecting
         common error conditions and recover as best as possible to allow the
         system to continue.
      
      J. Tracing
      
         Tracing can be enabled via the slab_debug=T,<slabcache> option
         during boot. SLUB will then protocol all actions on that slabcache
         and dump the object contents on free.
      
      K. On demand DMA cache creation.
      
         Generally DMA caches are not needed. If a kmalloc is used with
         __GFP_DMA then just create this single slabcache that is needed.
         For systems that have no ZONE_DMA requirement the support is
         completely eliminated.
      
      L. Performance increase
      
         Some benchmarks have shown speed improvements on kernbench in the
         range of 5-10%. The locking overhead of slub is based on the
         underlying base allocation size. If we can reliably allocate
         larger order pages then it is possible to increase slub
         performance much further. The anti-fragmentation patches may
         enable further performance increases.
      
      Tested on:
      i386 UP + SMP, x86_64 UP + SMP + NUMA emulation, IA64 NUMA + Simulator
      
      SLUB Boot options
      
      slub_nomerge		Disable merging of slabs
      slub_min_order=x	Require a minimum order for slab caches. This
      			increases the managed chunk size and therefore
      			reduces meta data and locking overhead.
      slub_min_objects=x	Mininum objects per slab. Default is 8.
      slub_max_order=x	Avoid generating slabs larger than order specified.
      slub_debug		Enable all diagnostics for all caches
      slub_debug=<options>	Enable selective options for all caches
      slub_debug=<o>,<cache>	Enable selective options for a certain set of
      			caches
      
      Available Debug options
      F		Double Free checking, sanity and resiliency
      R		Red zoning
      P		Object / padding poisoning
      U		Track last free / alloc
      T		Trace all allocs / frees (only use for individual slabs).
      
      To use SLUB: Apply this patch and then select SLUB as the default slab
      allocator.
      
      [hugh@veritas.com: fix an oops-causing locking error]
      [akpm@linux-foundation.org: various stupid cleanups and small fixes]
      Signed-off-by: NChristoph Lameter <clameter@sgi.com>
      Signed-off-by: NHugh Dickins <hugh@veritas.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      81819f0f
  13. 03 5月, 2007 1 次提交
  14. 07 3月, 2007 1 次提交
  15. 15 2月, 2007 1 次提交
  16. 12 2月, 2007 2 次提交
  17. 23 12月, 2006 2 次提交
  18. 13 12月, 2006 1 次提交
  19. 11 12月, 2006 1 次提交
    • A
      [PATCH] io-accounting: core statistics · 7c3ab738
      Andrew Morton 提交于
      The present per-task IO accounting isn't very useful.  It simply counts the
      number of bytes passed into read() and write().  So if a process reads 1MB
      from an already-cached file, it is accused of having performed 1MB of I/O,
      which is wrong.
      
      (David Wright had some comments on the applicability of the present logical IO accounting:
      
        For billing purposes it is useless but for workload analysis it is very
        useful
      
        read_bytes/read_calls  average read request size
        write_bytes/write_calls average write request size
      
        read_bytes/read_blocks ie logical/physical can indicate hit rate or thrashing
        write_bytes/write_blocks  ie logical/physical  guess since pdflush writes can
                                                      be missed
      
        I often look for logical larger than physical to see filesystem cache
        problems.  And the bytes/cpusec can help find applications that are
        dominating the cache and causing slow interactive response from page cache
        contention.
      
        I want to find the IO intensive applications and make sure they are doing
        efficient IO.  Thus the acctcms(sysV) or csacms command would give the high
        IO commands).
      
      This patchset adds new accounting which tries to be more accurate.  We account
      for three things:
      
      reads:
      
        attempt to count the number of bytes which this process really did cause
        to be fetched from the storage layer.  Done at the submit_bio() level, so it
        is accurate for block-backed filesystems.  I also attempt to wire up NFS and
        CIFS.
      
      writes:
      
        attempt to count the number of bytes which this process caused to be sent
        to the storage layer.  This is done at page-dirtying time.
      
        The big inaccuracy here is truncate.  If a process writes 1MB to a file
        and then deletes the file, it will in fact perform no writeout.  But it will
        have been accounted as having caused 1MB of write.
      
        So...
      
      cancelled_writes:
      
        account the number of bytes which this process caused to not happen, by
        truncating pagecache.
      
        We _could_ just subtract this from the process's `write' accounting.  But
        that means that some processes would be reported to have done negative
        amounts of write IO, which is silly.
      
        So we just report the raw number and punt this decision up to userspace.
      
      Now, we _could_ account for writes at the physical I/O level.  But
      
      - This would require that we track memory-dirtying tasks at the per-page
        level (would require a new pointer in struct page).
      
      - It would mean that IO statistics for a process are usually only available
        long after that process has exitted.  Which means that we probably cannot
        communicate this info via taskstats.
      
      This patch:
      
      Wire up the kernel-private data structures and the accessor functions to
      manipulate them.
      
      Cc: Jay Lan <jlan@sgi.com>
      Cc: Shailabh Nagar <nagar@watson.ibm.com>
      Cc: Balbir Singh <balbir@in.ibm.com>
      Cc: Chris Sturtivant <csturtiv@sgi.com>
      Cc: Tony Ernst <tee@sgi.com>
      Cc: Guillaume Thouvenin <guillaume.thouvenin@bull.net>
      Cc: David Wright <daw@sgi.com>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      7c3ab738
  20. 02 12月, 2006 1 次提交
  21. 09 11月, 2006 1 次提交
    • E
      [PATCH] sysctl: Undeprecate sys_sysctl · 13bb7e37
      Eric W. Biederman 提交于
      The basic issue is that despite have been deprecated and warned about as a
      very bad thing in the man pages since its inception there are a few real
      users of sys_sysctl.  It was my assumption that because sysctl had been
      deprecated for all of 2.6 there would be no user space users by this point,
      so I initially gave sys_sysctl a very short deprecation period.
      
      Now that I know there are a few real users the only sane way to proceed
      with deprecation is to push the time limit out to a year or two work and
      work with distributions that have big testing pools like fedora core to
      find these last remaining users.
      
      Which means that the sys_sysctl interface needs to be maintained in the
      meantime.
      
      Since I have provided a technical measure that allows us to add new sysctl
      entries without reserving more binary numbers I believe that is enough to
      fix the sys_sysctl binary interface maintenance problems, because there is
      no longer a need to change the binary interface at all.
      
      Since the sys_sysctl implementation needs to stay around for a while and
      the worst of the maintenance issues that caused us to occasionally break
      the ABI have been addressed I don't see any advantage in continuing with
      the removal of sys_sysctl.
      
      So instead of merely increasing the deprecation period this patch removes
      the deprecation of sys_sysctl and modifies the kernel to compile the code
      in by default.
      
      With committing to maintain sys_sysctl we get all of the advantages of a
      fast interface for anything that needs it.  Currently sys_sysctl is about
      5x faster than /proc/sys, for the same string data.
      Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
      Acked-by: NAlan Cox <alan@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      13bb7e37
  22. 21 10月, 2006 1 次提交
    • P
      [PATCH] uml: use DEFCONFIG_LIST to avoid reading host's config · b2670eac
      Paolo 'Blaisorblade' Giarrusso 提交于
      This should make sure that, for UML, host's configuration files are not
      considered, which avoids various pains to the user.  Our dependency are such
      that the obtained Kconfig will be valid and will lead to successful
      compilation - however they cannot prevent an user from disabling any boot
      device, and if an option is not set in the read .config (say
      /boot/config-XXX), with make menuconfig ARCH=um, it is not set.  This always
      disables UBD and all console I/O channels, which leads to non-working UML
      kernels, so this bothers users - especially now, since it will happen on
      almost every machine (/boot/config-`uname -r` exists almost on every machine).
       It can be workarounded with make defconfig ARCH=um, but it is non-obvious and
      can be avoided, so please _do_ merge this patch.
      
      Given the existence of options, it could be interesting to implement
      (additionally) "option required" - with it, Kconfig will refuse reading a
      .config file (from wherever it comes) if the given option is not set.  With
      this, one could mark with it the option characteristic of the given
      architecture (it was an old proposal of Roman Zippel, when I pointed out our
      problem):
      
      config UML
      	option required
      	default y
      
      However this should be further discussed:
      *) for x86, it must support constructs like:
      
      ==arch/i386/Kconfig==
      config 64BIT
      	option required
      	default n
      where Kconfig must require that CONFIG_64BIT is disabled or not present in the
      read .config.
      
      *) do we want to do such checks only for the starting defconfig or also for
         .config? Which leads to:
      *) I may want to port a x86_64 .config to x86 and viceversa, or even among more
         different archs. Should that be allowed, and in which measure (the user may
         force skipping the check for a .config or it is only given a warning by
         default)?
      
      Cc: Roman Zippel <zippel@linux-m68k.org>
      Cc: <kbuild-devel@lists.sourceforge.net>
      Signed-off-by: NPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
      Cc: Jeff Dike <jdike@addtoit.com>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      b2670eac
  23. 02 10月, 2006 2 次提交