From: olof@lixom•net (Olof Johansson)
To: Benjamin Herrenschmidt <benh@kernel•crashing.org>
Cc: Paul Mackerras <paulus@samba•org>,
cbe-oss-dev@ozlabs•org, Arnd Bergmann <arnd@arndb•de>,
linuxppc-dev@ozlabs•org
Subject: Re: [PATCH] 64K page support for kexec
Date: Tue, 24 Apr 2007 18:07:08 -0500 [thread overview]
Message-ID: <20070424230708.GA10401@lixom.net> (raw)
In-Reply-To: <1177455014.14873.144.camel@localhost.localdomain>
On Wed, Apr 25, 2007 at 08:50:14AM +1000, Benjamin Herrenschmidt wrote:
>
> > This assumes that the page sizes are ordered. Why not just iterate from
> > 0 to MMU_PAGE_COUNT?
>
> You don't want to hit MMU_PAGE_4K which is guaranteed to be 0 ... maybe
> just having an if (size == MMU_PAGE_4K) continue; statement in the loop
> would be better ?
Either that, or from 1 to MMU_PAGE_COUNT (with a comment as to why we're skipping
0).
> > > + /*
> > > + * FIXME, this could be made more efficient by storing the type
> > > + * of hash algorithm in mmu_psize_defs[]. The code below assumes
> > > + * the number of bits in the va representing the offset in the
> > > + * page is less than 23. This affects the hash algorithm that is
> > > + * used. When 16G pages are supported, a new hash algorithm
> > > + * needs to be provided. See POWER ISA Book III.
> > > + *
> > > + * The code below works for 16M, 64K, and 4K pages.
> > > + */
> >
> > A BUG_ON() when other sizes are hit could be a good idea?
>
> a BUG_ON if the B bit is set would be useful too. (that is 1T segment
> HPTE).
Yep.
> > > @@ -408,8 +453,9 @@ static void native_hpte_clear(void)
> > > * already hold the native_tlbie_lock.
> > > */
> > > if (hpte_v & HPTE_V_VALID) {
> > > + hpte_decode(hptep, slot, &psize, &hpte_v);
> > > hptep->v = 0;
> > > - __tlbie(slot2va(hpte_v, slot), MMU_PAGE_4K);
> > > + __tlbie(hpte_v, psize);
> >
> > Using hpte_v as variable name is a bit misleading. avpn or va would be
> > a better variable name.
>
> No. The variable doesn't contain only the va, it contains the whole "V"
> part of the HPTE which includes other things like the valid bit.
Ok. The previous usage was confusing me (given that they did a translation
from hpte_v to va, or at least that's what the function name implies).
-Olof
next prev parent reply other threads:[~2007-04-24 23:07 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-24 18:31 [PATCH] 64K page support for kexec Luke Browning
2007-04-24 19:43 ` Olof Johansson
2007-04-24 22:50 ` Benjamin Herrenschmidt
2007-04-24 23:07 ` Olof Johansson [this message]
2007-04-25 5:48 ` Milton Miller
2007-04-25 19:35 ` [PATCH v2] powerpc: " Luke Browning
2007-04-25 22:19 ` Benjamin Herrenschmidt
2007-04-26 15:28 ` Luke Browning
2007-04-27 4:36 ` [PATCH v3] " Milton Miller
2007-04-27 14:42 ` Luke Browning
2007-04-27 16:51 ` Milton Miller
2007-04-27 16:22 ` [PATCH v4] " Luke Browning
2007-04-27 16:59 ` Milton Miller
2007-04-27 17:30 ` Luke Browning
2007-04-27 18:23 ` Haren Myneni
2007-04-29 5:35 ` Milton Miller
2007-04-29 8:30 ` Paul Mackerras
2007-04-29 9:31 ` Benjamin Herrenschmidt
2007-04-29 13:27 ` Segher Boessenkool
2007-04-29 22:49 ` Benjamin Herrenschmidt
2007-04-26 7:15 ` [PATCH v2] " Olof Johansson
2007-04-24 22:48 ` [PATCH] " Benjamin Herrenschmidt
2007-04-25 13:06 ` Luke Browning
2007-04-25 22:11 ` Benjamin Herrenschmidt
-- strict thread matches above, loose matches on Subject: below --
2007-04-26 22:23 [PATCH v3] powerpc: " Luke Browning
2007-04-26 22:32 ` Olof Johansson
2007-05-02 14:19 ` [PATCH v4] " Luke Browning
2007-05-03 13:45 ` Arnd Bergmann
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