linux-kernel - Re: [PATCH] powerpc: enable a 30-bit ZONE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <d508cc9c-435f-4108-17ac-6db74640514c@lwfinger.net>
Date:   Fri, 14 Jun 2019 15:26:31 -0500
From:   Larry Finger <Larry.Finger@...inger.net>
To:     Aaro Koskinen <aaro.koskinen@....fi>,
        Mathieu Malaterre <malat@...ian.org>
Cc:     Christoph Hellwig <hch@....de>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] powerpc: enable a 30-bit ZONE_DMA for 32-bit pmac

On 6/14/19 2:15 PM, Aaro Koskinen wrote:
> Hi,
> 
> On Fri, Jun 14, 2019 at 09:24:16AM +0200, Mathieu Malaterre wrote:
>> On Thu, Jun 13, 2019 at 10:27 AM Christoph Hellwig <hch@....de> wrote:
>>> With the strict dma mask checking introduced with the switch to
>>> the generic DMA direct code common wifi chips on 32-bit powerbooks
>>> stopped working.  Add a 30-bit ZONE_DMA to the 32-bit pmac builds
>>> to allow them to reliably allocate dma coherent memory.
>>>
>>> Fixes: 65a21b71f948 ("powerpc/dma: remove dma_nommu_dma_supported")
>>> Reported-by: Aaro Koskinen <aaro.koskinen@....fi>
>>> Signed-off-by: Christoph Hellwig <hch@....de>
>>> ---
>>>   arch/powerpc/include/asm/page.h         | 7 +++++++
>>>   arch/powerpc/mm/mem.c                   | 3 ++-
>>>   arch/powerpc/platforms/powermac/Kconfig | 1 +
>>>   3 files changed, 10 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
>>> index b8286a2013b4..0d52f57fca04 100644
>>> --- a/arch/powerpc/include/asm/page.h
>>> +++ b/arch/powerpc/include/asm/page.h
>>> @@ -319,6 +319,13 @@ struct vm_area_struct;
>>>   #endif /* __ASSEMBLY__ */
>>>   #include <asm/slice.h>
>>>
>>> +/*
>>> + * Allow 30-bit DMA for very limited Broadcom wifi chips on many powerbooks.
>>
>> nit: would it be possible to mention explicit reference to b43-legacy.
>> Using b43 on my macmini g4 never showed those symptoms (using
>> 5.2.0-rc2+)
> 
> According to Wikipedia Mac mini G4 is limited to 1 GB RAM, so that's
> why you don't see the issue.

He wouldn't see it with b43. Those cards have 32-bit DMA.

Larry