From: robin.murphy@arm.com (Robin Murphy)
To: linux-arm-kernel@lists.infradead.org
Subject: [Question] Memory attribute reserved by Device Tree?
Date: Thu, 30 Jun 2016 12:39:03 +0100 [thread overview]
Message-ID: <577504D7.7080106@arm.com> (raw)
In-Reply-To: <CAK7LNATGoP-Wn-wiK_CgD_v=rQXyt937qRvr8LkUQ06jHB7FAA@mail.gmail.com>
On 30/06/16 12:10, Masahiro Yamada wrote:
> Hello.
>
> Which memory attribute will ARM/ARM64 Linux
> set to the memory region reserved by
> /memreserve/ of Device Tree?
>
>
> Normal memory non-cacheable?
> Or, cacheable?
> Or, not defined?
>
> Perhaps actual behavior depends on whether the reserved area is
> located in the low-memory region?
Isn't the point of memreserve that the kernel avoids mapping it at all?
If a reserved region is later mapped in by a driver using
dma_declare_coherent_memory(), ioremap(), memremap() or whatever else,
then the attributes will vary depending on the exact method used.
Robin.
>
>
> Thanks,
>
>
WARNING: multiple messages have this Message-ID (diff)
From: Robin Murphy <robin.murphy@arm.com>
To: Masahiro Yamada <yamada.masahiro@socionext.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
devicetree@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Subject: Re: [Question] Memory attribute reserved by Device Tree?
Date: Thu, 30 Jun 2016 12:39:03 +0100 [thread overview]
Message-ID: <577504D7.7080106@arm.com> (raw)
In-Reply-To: <CAK7LNATGoP-Wn-wiK_CgD_v=rQXyt937qRvr8LkUQ06jHB7FAA@mail.gmail.com>
On 30/06/16 12:10, Masahiro Yamada wrote:
> Hello.
>
> Which memory attribute will ARM/ARM64 Linux
> set to the memory region reserved by
> /memreserve/ of Device Tree?
>
>
> Normal memory non-cacheable?
> Or, cacheable?
> Or, not defined?
>
> Perhaps actual behavior depends on whether the reserved area is
> located in the low-memory region?
Isn't the point of memreserve that the kernel avoids mapping it at all?
If a reserved region is later mapped in by a driver using
dma_declare_coherent_memory(), ioremap(), memremap() or whatever else,
then the attributes will vary depending on the exact method used.
Robin.
>
>
> Thanks,
>
>
next prev parent reply other threads:[~2016-06-30 11:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-30 11:10 [Question] Memory attribute reserved by Device Tree? Masahiro Yamada
2016-06-30 11:10 ` Masahiro Yamada
2016-06-30 11:39 ` Robin Murphy [this message]
2016-06-30 11:39 ` Robin Murphy
2016-06-30 12:26 ` Mark Rutland
2016-06-30 12:26 ` Mark Rutland
2016-07-06 4:10 ` Masahiro Yamada
2016-07-06 4:10 ` Masahiro Yamada
2016-07-06 5:34 ` Ard Biesheuvel
2016-07-06 5:34 ` Ard Biesheuvel
2016-07-06 9:34 ` Mark Rutland
2016-07-06 9:34 ` Mark Rutland
2016-07-06 9:48 ` Ard Biesheuvel
2016-07-06 9:48 ` Ard Biesheuvel
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