linux-kernel - Re: [PATCH 14/28] nios2: DMA mapping API

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: <CAFiDJ58__vjDk93crSxGe1us0K7a3kSUwScgk=VaJYy+VqXsWQ@mail.gmail.com>
Date:	Fri, 25 Apr 2014 18:13:31 +0800
From:	Ley Foon Tan <lftan@...era.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Linux-Arch <linux-arch@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	cltang@...esourcery.com
Subject: Re: [PATCH 14/28] nios2: DMA mapping API

On Tue, Apr 22, 2014 at 9:52 PM, Arnd Bergmann <arnd@...db.de> wrote:
> On Friday 18 April 2014, Ley Foon Tan wrote:
>
>> +static inline int dma_supported(struct device *dev, u64 mask)
>> +{
>> +     /* we fall back to GFP_DMA when the mask isn't all 1s,
>> +      * so we can't guarantee allocations that must be
>> +      * within a tighter range than GFP_DMA.
>> +      */
>> +     if (mask < 0x00ffffff)
>> +             return 0;
>> +
>> +     return 1;
>> +}
>
>> +void *dma_alloc_coherent(struct device *dev, size_t size,
>> +                         dma_addr_t *dma_handle, gfp_t gfp)
>> +{
>> +     void *ret;
>> +
>> +     /* ignore region specifiers */
>> +     gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
>> +
>> +     /* optimized page clearing */
>> +     gfp |= __GFP_ZERO;
>> +
>> +     if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
>> +             gfp |= GFP_DMA;
>
> What is the significance of ZONE_DMA on this architecture?
>
> Do you actually have DMA masters with a 0x00ffffff mask?
Actually, nios2 doesn't have DMA master with 0x00ffffff mask. I will
change it to return 1, same as some other architectures
implementation.
And the ZONE_DMA stuff will remove as well, it shouldn't have ZONE_DMA
limitation.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/