linux-kernel - Re: [PATCH] x86: devicetree: fix config option around x86_flattree_get

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Date:   Sat, 3 Mar 2018 12:17:28 -0800
From:   Frank Rowand <frowand.list@...il.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Rob Herring <robh+dt@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     Ivan Gorinov <ivan.gorinov@...el.com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, geert@...ux-m68k.org,
        laurent.pinchart+renesas@...asonboard.com
Subject: Re: [PATCH] x86: devicetree: fix config option around
 x86_flattree_get_config()

Hi x86 Maintainers,

On 03/03/18 01:17, Laurent Pinchart wrote:
> Hi Frank,
> 
> Thank you for the patch.
> 
> On Saturday, 3 March 2018 06:12:26 EET frowand.list@...il.com wrote:
>> From: Frank Rowand <frank.rowand@...y.com>
>>
>> x86_flattree_get_config() is incorrectly protected by
>> ifdef CONFIG_OF_FLATTREE.  It uses of_get_flat_dt_size(), which
>> only exists if CONFIG_OF_EARLY_FLATTREE.  This issue has not
>> been exposed previously because OF_FLATTREE did not occur unless
>> it was selected by OF_EARLY_FLATTREE.  A devicetree overlay change
>> is selecting OF_FLATTREE directly instead of indirectly enabling
>> it by selecting OF_EARLY_FLATTREE.
>>
>> This problem was exposed by a randconfig generated by the kbuild
>> test robot, where Platform OLPC was enabled.  OLPC selects
>> OF_PROMTREE instead of OF_EARLY_FLATREE.  The only other x86
>> platform that selects OF is X86_INTEL_CE, which does select
>> OF_EARLY_FLATTREE.
>>
>> Signed-off-by: Frank Rowand <frank.rowand@...y.com>
>> ---
>>
>> The devicetree overlay change is in patch 1/4 of the series:
>> https://lkml.org/lkml/2018/3/2/979
>>
>> The pull request for the patch series that triggered the kbuild
>> test robot is:
>> https://lkml.org/lkml/2018/3/2/1065
>>
>>  arch/x86/kernel/devicetree.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
>> index 25de5f6ca997..45416826f6ee 100644
>> --- a/arch/x86/kernel/devicetree.c
>> +++ b/arch/x86/kernel/devicetree.c
>> @@ -259,7 +259,7 @@ static void __init dtb_apic_setup(void)
>>  	dtb_ioapic_setup();
>>  }
>>
>> -#ifdef CONFIG_OF_FLATTREE
>> +#ifdef CONFIG_OF_EARLY_FLATTREE
>>  static void __init x86_flattree_get_config(void)
>>  {
>>  	u32 size, map_len;
> 
> This looks good to me. Could you respin the pull request with this patch 
> included ? I need to send a pull request for a patch series based on your 
> overlay changes, and I'd rather avoid breaking the build :-)
> 

I sent this patch to the x86 maintainers and to Rob because of a patch
series that is modifying arch/x86/kernel/devicetree.c, in
x86_flattree_get_config() [1].  It does not look like my patch will
conflict with that patch at the moment, but it is possible that a conflict
could develop as that patch is developed.

I will add this patch to my devictree pull request, and ask the x86
maintainers to ack it and watch for possible conflicts as patch [1]
is further developed.


[1] https://lkml.org/lkml/2018/3/1/1005
    [PATCH v3 1/3] x86: devicetree: call early_init_dt_verify()