Re: -fno-strict-aliasing

From: Robert Dinse (nanook@eskimo.com)
Date: Tue Apr 18 2000 - 21:09:53 EDT

  • Next message: Robert Dinse: "-fno-strict-aliasing"

    On Tue, 18 Apr 2000, Giacomo Catenazzi wrote:
    >
    > > I've had these Sparc spin-lock from hell problems on all 2.2.x
    > > kernels running on SMP SS-10's or SS-20's with Ross Hypersparc CPU's.
    > > I read in a newsgroup recently someone else having the same problem
    > > and removing the -no-strict-aliasing option helped them. But I built
    > > a kernel without it and the kernels ended up exactly the same size so
    > > I don't know if it actually made any difference in the generated code
    > > or not.
    >
    > What compiler do you use?

         With 2.2.14, I've used egcs-2.91.66, egcs-2.90.27, and several 2.95
    versions, I think 2.95.1 and 2.95.2, and whatever came with RedHat, but only
    the former two do I still have on my system at present. The egcs-2.90.27
    compiled kernel runs fine on a 4/670MP platform but spinlocks on SS-10 or SS-20
    even though the exact SAME (as in physically removed from one box and placed in
    the other) CPU's are used, same amount of RAM also (384MB).

         I've tried compiling with just -O1 optimization, lasted about 30 hours
    before a spinlock. Strangely, if I try to compile with -O0 (no optimization)
    it explodes during the loading phase, something about bitfix or some such. I'd
    have to attempt it again to give the exact error message.

         There is something architecture dependent because it doesn't do it on the
    4/670MP, but the SS-10 will run SunOS with 100 users doing various things for
    on average about a month between crashes (and then more often than not it is
    denial of service attacks eating up all mbufs), where Linux will only last on
    average 1-2 days between spin_lock deadlock, and I've had the same behavior
    under Linux on three different boxes, so I don't think it is defective hardware
    that just happens to only affect Linux.

         So far, the only 2.3.x kernels I've been successful at getting to build
    wouldn't even boot on these machines, or on the Ultra-1, or on a PC I have here
    for that matter. Probably some operator error but I haven't figured out what
    yet, it does the twirling cursor bit and then locks.

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