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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Arnd Bergmann <arnd@arndb.de>, Milton Miller <miltonm@bga.com>,
	linuxppc-dev@ozlabs.org, Paul Mackerras <paulus@samba.org>,
	Olof Johansson <olof@lixom.net>,
	cbe-oss-dev@ozlabs.org
Subject: Re: [PATCH v4] powerpc: 64K page support for kexec
Date: Mon, 30 Apr 2007 08:49:51 +1000	[thread overview]
Message-ID: <1177886991.14873.368.camel@localhost.localdomain> (raw)
In-Reply-To: <c08e2dc179070866364d96a7b5ade65b@kernel.crashing.org>

On Sun, 2007-04-29 at 15:27 +0200, Segher Boessenkool wrote:
> >>   BUG_ON((hpte_v & 0x4000000000000000UL) && (crashing_cpus == -1));
> >>   BUG_ON((size == MMU_PAGE_16G) && (crashing_cpus == -1));
> >>   BUG_ON((size == MMU_PAGE_64K_AP) && (crashing_cpus == -1));
> >
> > How much effort would it be to add the code to cope with those
> > conditions and give the correct answers?  I'd much prefer that to
> > these BUG_ONs.
> 
> The test "& 0x400..." should be "& 0xc00..." since the
> "B" filed in a page table entry is the top _two_ bits.

Yup, we need to put some symbolic constants too. We can dig them from
the old never-applied 1T segment patch I did a while ago.

> Not sure what that tells us about the work involved in
> making this code do the right thing under all conditions,
> but it would seem to indicate trouble ahead.  Also, the
> encodings with bit 0 = 1 are reserved (says arch v2.03),
> so there would probably still be a BUG_ON() here.

Ben.

  reply	other threads:[~2007-04-29 22:49 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
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 [this message]
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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