From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 2/2] ARM : change fixmap mapping region to support 32 CPUs
Date: Fri, 30 May 2014 19:02:12 +0100 [thread overview]
Message-ID: <20140530180212.GF22895@arm.com> (raw)
In-Reply-To: <CAL_JsqKE-L2PN3mXHNdTPMEyTMR9ZtbgGB=O_V6nOXN0YC0a4A@mail.gmail.com>
On Fri, May 30, 2014 at 04:33:46PM +0100, Rob Herring wrote:
> On Tue, Apr 15, 2014 at 6:06 AM, Liu Hua <sdu.liu@huawei.com> wrote:
> > In 32-bit ARM systems, the fixmap mapping region can support
> > no more than 14 CPUs(total: 896k; one CPU: 64K). And we can
> > configure NR_CPUS up to 32. So there is a mismatch.
> >
> > This patch moves fixmapping region downwards to region
> > 0xffc00000-0xffe00000. Then the fixmap mapping region can
> > support up to 32 CPUs
>
> Ugg, this series breaks using fixmap for anything other than kmap
> since 32 cpus requires all 2MB of the region and nothing is left.
> There's work in flight to support early_ioremap, early console, and RO
> text patching which all use the fixmap region.
>
> There's a couple of options to solve this:
>
> - Only support up to 16 cpus. It could be anywhere between 17-31, but
> that seems somewhat unlikely. Are we really ever going to see 32-bit
> 32 core systems?
I'd be fine with restricting the limit to 16 CPUs.
Will
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon@arm.com>
To: Rob Herring <robherring2@gmail.com>
Cc: Liu Hua <sdu.liu@huawei.com>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
Nicolas Pitre <nicolas.pitre@linaro.org>,
"wangnan0@huawei.com" <wangnan0@huawei.com>,
Laura Abbott <lauraa@codeaurora.org>,
"peifeiyue@huawei.com" <peifeiyue@huawei.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"vitalya@ti.com" <vitalya@ti.com>,
Santosh Shilimkar <santosh.shilimkar@ti.com>,
"liusdu@126.co" <liusdu@126.co>, "cyril@ti.com" <cyril@ti.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Rabin Vincent <rabin@rab.in>
Subject: Re: [PATCH v3 2/2] ARM : change fixmap mapping region to support 32 CPUs
Date: Fri, 30 May 2014 19:02:12 +0100 [thread overview]
Message-ID: <20140530180212.GF22895@arm.com> (raw)
In-Reply-To: <CAL_JsqKE-L2PN3mXHNdTPMEyTMR9ZtbgGB=O_V6nOXN0YC0a4A@mail.gmail.com>
On Fri, May 30, 2014 at 04:33:46PM +0100, Rob Herring wrote:
> On Tue, Apr 15, 2014 at 6:06 AM, Liu Hua <sdu.liu@huawei.com> wrote:
> > In 32-bit ARM systems, the fixmap mapping region can support
> > no more than 14 CPUs(total: 896k; one CPU: 64K). And we can
> > configure NR_CPUS up to 32. So there is a mismatch.
> >
> > This patch moves fixmapping region downwards to region
> > 0xffc00000-0xffe00000. Then the fixmap mapping region can
> > support up to 32 CPUs
>
> Ugg, this series breaks using fixmap for anything other than kmap
> since 32 cpus requires all 2MB of the region and nothing is left.
> There's work in flight to support early_ioremap, early console, and RO
> text patching which all use the fixmap region.
>
> There's a couple of options to solve this:
>
> - Only support up to 16 cpus. It could be anywhere between 17-31, but
> that seems somewhat unlikely. Are we really ever going to see 32-bit
> 32 core systems?
I'd be fine with restricting the limit to 16 CPUs.
Will
next prev parent reply other threads:[~2014-05-30 18:02 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-15 11:06 [PATCH v3 0/2] change ARM linux memory layout to support 32 CPUs Liu Hua
2014-04-15 11:06 ` Liu Hua
2014-04-15 11:06 ` [PATCH v3 1/2] ARM : fixmap : remove FIX_KMAP_BEGIN and FIX_KMAP_END Liu Hua
2014-04-15 11:06 ` Liu Hua
2014-04-15 11:06 ` [PATCH v3 2/2] ARM : change fixmap mapping region to support 32 CPUs Liu Hua
2014-04-15 11:06 ` Liu Hua
2014-04-15 15:06 ` Nicolas Pitre
2014-04-15 15:06 ` Nicolas Pitre
2014-05-30 15:33 ` Rob Herring
2014-05-30 15:33 ` Rob Herring
2014-05-30 18:02 ` Will Deacon [this message]
2014-05-30 18:02 ` Will Deacon
2014-05-30 19:25 ` Nicolas Pitre
2014-05-30 19:25 ` Nicolas Pitre
2014-06-10 6:52 ` Liu hua
2014-06-10 6:52 ` Liu hua
2014-08-06 2:51 ` Kees Cook
2014-08-06 2:51 ` Kees Cook
2014-08-06 3:11 ` Nicolas Pitre
2014-08-06 3:11 ` Nicolas Pitre
2014-08-06 3:40 ` Liu hua
2014-08-06 3:40 ` Liu hua
2014-08-06 16:37 ` Kees Cook
2014-08-06 16:37 ` Kees Cook
2014-08-06 17:21 ` Nicolas Pitre
2014-08-06 17:21 ` Nicolas Pitre
2014-08-06 17:28 ` Kees Cook
2014-08-06 17:28 ` Kees Cook
2014-08-06 22:16 ` Russell King - ARM Linux
2014-08-06 22:16 ` Russell King - ARM Linux
2014-08-06 23:22 ` Kees Cook
2014-08-06 23:22 ` Kees Cook
2014-04-22 21:31 ` [PATCH v3 0/2] change ARM linux memory layout " Russell King - ARM Linux
2014-04-22 21:31 ` Russell King - ARM Linux
2014-04-22 23:50 ` Nicolas Pitre
2014-04-22 23:50 ` Nicolas Pitre
2014-05-04 2:34 ` Liu hua
2014-05-04 2:34 ` Liu hua
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