From: Michael Neuling <mikey@neuling•org>
To: David Gibson <david@gibson•dropbear.id.au>
Cc: linuxppc-dev@ozlabs•org
Subject: Re: [PATCH 4/16] powerpc: Allow duplicate lmb_reserve() calls
Date: Tue, 13 Feb 2007 18:05:20 +1100 [thread overview]
Message-ID: <21160.1171350320@neuling.org> (raw)
In-Reply-To: <20070213061024.82D45DDD0D@ozlabs.org>
> At present calling lmb_reserve() (and hence lmb_add_region()) twice
> for exactly the same memory region will cause strange behaviour.
>
> This makes life difficult when booting from a flat device tree with
> memory reserve map. Which regions are automatically reserved by the
> kernel has changed over time, so it's quite possible a newer kernel
> could attempt to auto-reserve a region which is also explicitly listed
> in the device tree's reserve map, leading to trouble.
>
> This patch avoids the problem by making lmb_reserve() ignore a call to
> reserve a previously reserved region. It also removes a now redundant
> test designed to avoid one specific case of the problem noted above.
>
> At present, this patch deals only with duplicate reservations of an
> identical region. Attempting to reserve two different, but
> overlapping regions will still cause problems. I might post another
> patch later dealing with this case, but I'm avoiding it now since it
> is substantially more complicated to deal with, less likely to occur
> and more likely to indicate a genuine bug elsewhere if it does occur.
>
> Signed-off-by: David Gibson <dwg@au1•ibm.com>
> ---
>
>
> arch/powerpc/kernel/prom.c | 3 ---
> arch/powerpc/mm/lmb.c | 4 ++++
> 2 files changed, 4 insertions(+), 3 deletions(-)
>
> Index: working-2.6/arch/powerpc/mm/lmb.c
> ===================================================================
> --- working-2.6.orig/arch/powerpc/mm/lmb.c 2007-02-06 16:21:02.000000000 +
1100
> +++ working-2.6/arch/powerpc/mm/lmb.c 2007-02-06 16:22:32.000000000 +1100
> @@ -146,6 +146,10 @@ static long __init lmb_add_region(struct
> unsigned long rgnbase = rgn->region[i].base;
> unsigned long rgnsize = rgn->region[i].size;
>
> + if ((rgnbase == base) && (rgnsize == size))
> + /* Already have this region, so we're done */
> + return 0;
This might indicate that two things actually want to use the same memory
region. How about we print a warning?
Mikey
next prev parent reply other threads:[~2007-02-13 7:05 UTC|newest]
Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-13 6:09 [0/16] Preliminary Ebony (440GP) support for arch/powerpc David Gibson
2007-02-13 6:10 ` [PATCH 8/16] Define FIXED_PORT flag for serial_core David Gibson
2007-02-13 6:10 ` [PATCH 6/16] Port 44x MMU definitions to ARCH=powerpc David Gibson
2007-02-13 6:24 ` Benjamin Herrenschmidt
2007-02-13 17:13 ` Roland Dreier
2007-02-13 17:45 ` Josh Boyer
2007-02-13 21:36 ` Benjamin Herrenschmidt
2007-02-13 6:10 ` [PATCH 2/16] More DCR native fixups David Gibson
2007-02-13 6:22 ` Benjamin Herrenschmidt
2007-02-13 6:10 ` [PATCH 1/16] Remove ibm4{xx,4x}.h from arch/powerpc David Gibson
2007-02-13 14:19 ` Josh Boyer
2007-02-13 6:10 ` [PATCH 5/16] powerpc: Add zImage platform hook for kernel address David Gibson
2007-02-13 6:10 ` [PATCH 7/16] Early serial debug support for PPC44x David Gibson
2007-02-13 15:04 ` Josh Boyer
2007-02-14 0:16 ` David Gibson
2007-02-14 1:02 ` Josh Boyer
2007-02-14 1:00 ` David Gibson
2007-02-14 2:00 ` Alan Modra
2007-02-14 2:02 ` David Gibson
2007-02-14 2:38 ` Alan Modra
2007-02-14 15:41 ` Josh Boyer
2007-02-14 23:05 ` David Gibson
2007-02-13 6:10 ` [PATCH 3/16] [powerpc] Use udbg_early_init() on ppc32 David Gibson
2007-02-13 6:22 ` Benjamin Herrenschmidt
2007-02-13 6:10 ` [PATCH 4/16] powerpc: Allow duplicate lmb_reserve() calls David Gibson
2007-02-13 7:05 ` Michael Neuling [this message]
2007-02-13 8:48 ` Michael Ellerman
2007-02-13 20:44 ` Benjamin Herrenschmidt
2007-02-13 6:10 ` [PATCH 14/16] Add arch/powerpc driver for UIC, PPC4xx interrupt controller David Gibson
2007-02-13 6:10 ` [PATCH 11/16] zImage wrapper for Ebony David Gibson
2007-02-13 17:05 ` Geoff Levand
2007-02-14 0:17 ` David Gibson
2007-02-13 6:10 ` [PATCH 13/16] Add initrd properties to device tree from zImage David Gibson
2007-02-13 6:10 ` [PATCH 9/16] Use resource_size_t for serial port IO addresses David Gibson
2007-02-13 6:10 ` [PATCH 12/16] Automatically lmb_reserve() initrd David Gibson
2007-02-13 7:14 ` Michael Neuling
2007-02-13 6:10 ` [PATCH 10/16] Add support for BSS stack for zImage wrapper David Gibson
2007-02-13 6:10 ` [PATCH 15/16] Add device tree for Ebony David Gibson
2007-02-13 20:08 ` Segher Boessenkool
2007-02-14 0:22 ` David Gibson
2007-02-14 1:51 ` Benjamin Herrenschmidt
2007-02-14 4:46 ` David Gibson
2007-02-14 17:54 ` Segher Boessenkool
2007-02-14 23:18 ` David Gibson
2007-02-15 0:25 ` Segher Boessenkool
2007-02-14 17:51 ` Segher Boessenkool
2007-02-14 17:48 ` Segher Boessenkool
2007-02-14 21:30 ` Benjamin Herrenschmidt
2007-02-15 0:03 ` Segher Boessenkool
2007-02-15 0:53 ` Benjamin Herrenschmidt
2007-02-15 1:00 ` Segher Boessenkool
2007-02-15 2:22 ` Benjamin Herrenschmidt
2007-02-15 2:51 ` Segher Boessenkool
2007-02-14 23:17 ` David Gibson
2007-02-15 0:27 ` Segher Boessenkool
2007-02-15 14:02 ` Jon Loeliger
2007-02-15 14:56 ` Segher Boessenkool
2007-02-15 17:02 ` Yoder Stuart-B08248
2007-02-15 17:10 ` Scott Wood
2007-02-16 9:20 ` Segher Boessenkool
2007-02-14 16:14 ` Yoder Stuart-B08248
2007-02-14 16:32 ` Josh Boyer
2007-02-14 17:58 ` Segher Boessenkool
2007-02-14 20:08 ` Yoder Stuart-B08248
2007-02-14 21:12 ` Segher Boessenkool
2007-02-14 21:35 ` Yoder Stuart-B08248
2007-02-14 21:42 ` Benjamin Herrenschmidt
2007-02-14 21:59 ` Scott Wood
2007-02-15 0:20 ` Segher Boessenkool
2007-02-14 22:50 ` Yoder Stuart-B08248
2007-02-14 22:57 ` Benjamin Herrenschmidt
2007-02-15 0:17 ` Segher Boessenkool
2007-02-15 2:12 ` Paul Mackerras
2007-02-15 2:43 ` Segher Boessenkool
2007-02-15 3:15 ` Paul Mackerras
2007-02-15 14:40 ` Segher Boessenkool
2007-02-16 1:17 ` Paul Mackerras
2007-02-16 9:41 ` Segher Boessenkool
2007-02-15 0:10 ` Segher Boessenkool
2007-02-14 23:32 ` David Gibson
2007-02-14 23:27 ` David Gibson
2007-02-14 23:22 ` David Gibson
2007-02-14 23:51 ` Benjamin Herrenschmidt
2007-02-15 0:36 ` Segher Boessenkool
2007-02-15 0:31 ` Segher Boessenkool
2007-02-15 1:53 ` David Gibson
2007-02-15 3:09 ` Segher Boessenkool
2007-02-15 3:33 ` David Gibson
2007-02-15 14:47 ` Segher Boessenkool
2007-02-15 10:52 ` Benjamin Herrenschmidt
2007-02-15 14:52 ` Segher Boessenkool
2007-02-15 20:43 ` Benjamin Herrenschmidt
2007-02-16 9:23 ` Segher Boessenkool
2007-02-15 16:37 ` Yoder Stuart-B08248
2007-02-15 21:41 ` Benjamin Herrenschmidt
2007-02-16 9:25 ` Segher Boessenkool
2007-02-16 15:32 ` Hartmut Penner
2007-02-16 16:47 ` Yoder Stuart-B08248
2007-02-19 12:02 ` Hartmut Penner
2007-02-14 21:29 ` Benjamin Herrenschmidt
2007-02-13 6:10 ` [PATCH 16/16] Support for Ebony in arch/powerpc David Gibson
2007-02-13 17:18 ` Roland Dreier
2007-02-14 0:20 ` David Gibson
2007-02-13 14:37 ` [0/16] Preliminary Ebony (440GP) support for arch/powerpc Josh Boyer
2007-02-13 20:21 ` Josh Boyer
2007-02-13 15:46 ` Josh Boyer
2007-02-14 16:06 ` Josh Boyer
2007-02-14 23:12 ` David Gibson
2007-02-16 2:19 ` Josh Boyer
2007-02-16 2:53 ` David Gibson
2007-02-16 4:33 ` Josh Boyer
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