Re: [patch] linux 2.4.17: The second mb() rework (final)

On Fri, 15 Feb 2002, Kevin D. Kissell wrote:

quoted

 The code is not correct if "bc0f" is needed to be sure a write-back
happened.  If that is the case, the processors need their own wbflush() 
implementation like R2k/R3k configurations in older DECstations. 

Note that I did not say that "the code is correct", only that it
is correct *in considering the TX39 to be effectively SYNC-less*.

 Then you are probably misinterpreting CONFIG_CPU_HAS_SYNC (shame on me
for not documenting it at all).  It means a CPU has the "sync" 
instruction but it does not imply a "sync" is sufficient for mb() on the
CPU.  See the code in include/asm-mips/system.h in my patch.  If
CONFIG_CPU_HAS_WB is set wbflush() is executed for mb() regardless the
setting of CONFIG_CPU_HAS_SYNC.  Fast_mb() is set to a "sync" in case a
wbflush() implementation needs it for something -- the DECstation's
wbflush() actually uses it in a patch I have queued waiting for my
pending submissions to be applied by Ralf.

I'm sure that the code is anyway broken six ways from Wednesday,
as usual.  ;-)

 I hope with my fixes the number of ways decreases, though. ;-) 

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +