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From: AKASHI Takahiro <takahiro.akashi@linaro.org>
To: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Pratyush Anand <panand@redhat.com>,
	geoff@infradead.org, catalin.marinas@arm.com,
	kexec@lists.infradead.org, will.deacon@arm.com,
	james.morse@arm.com, Mark Salter <msalter@redhat.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v21 1/8] arm64: kdump: reserve memory for crash dump kernel
Date: Thu, 7 Jul 2016 10:17:47 +0900	[thread overview]
Message-ID: <20160707011745.GX20774@linaro.org> (raw)
In-Reply-To: <2543175.KeBui093Sr@hactar>

On Wed, Jul 06, 2016 at 03:11:45PM -0300, Thiago Jung Bauermann wrote:
> Am Mittwoch, 06 Juli 2016, 16:52:19 schrieb AKASHI Takahiro:
> > On the startup of primary kernel, the memory region used by crash dump
> > kernel must be specified by "crashkernel=" kernel parameter.
> > reserve_crashkernel() will allocate and reserve the region for later use.
> > 
> > User space tools, like kexec-tools, will be able to find that region
> > marked as "Crash kernel" in /proc/iomem.
> 
> On powerpc, userspace tools get everything from the device tree (exposed to 
> userspace in /proc/device-tree/), not /proc/iomem.

I started my kdump patches with arm (not arm64) implementation, and
so /proc/iomem is used for consistency. Since my kexec-tools (for arm64)
have to access /proc/iomem to identify usable memory regions on
*UEFI* systems anyway, I didn't think it was odd.

(Please note that UEFI won't expose memory regions information via
a device tree, but via ACPI table.)

> In the case of the crashkernel reserved region, that information is in 
> /chosen/linux,crashkernel-base and /chosen/linux,crashkernel-size.
> 
> Either way is fine I think. I'm just mentioning this for reference in case 
> you want the ARM implementation to be closer to another arch which is also 
> based on the device tree.

Adding those properties to a device tree is quite easy
(and it won't conflict with /proc/iomem), so I'd like 
to defer to arm64 maintainers.

Thanks,
-Takahiro AKASHI

> -- 
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
> 

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kexec@lists.infradead.org
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WARNING: multiple messages have this Message-ID (diff)
From: takahiro.akashi@linaro.org (AKASHI Takahiro)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v21 1/8] arm64: kdump: reserve memory for crash dump kernel
Date: Thu, 7 Jul 2016 10:17:47 +0900	[thread overview]
Message-ID: <20160707011745.GX20774@linaro.org> (raw)
In-Reply-To: <2543175.KeBui093Sr@hactar>

On Wed, Jul 06, 2016 at 03:11:45PM -0300, Thiago Jung Bauermann wrote:
> Am Mittwoch, 06 Juli 2016, 16:52:19 schrieb AKASHI Takahiro:
> > On the startup of primary kernel, the memory region used by crash dump
> > kernel must be specified by "crashkernel=" kernel parameter.
> > reserve_crashkernel() will allocate and reserve the region for later use.
> > 
> > User space tools, like kexec-tools, will be able to find that region
> > marked as "Crash kernel" in /proc/iomem.
> 
> On powerpc, userspace tools get everything from the device tree (exposed to 
> userspace in /proc/device-tree/), not /proc/iomem.

I started my kdump patches with arm (not arm64) implementation, and
so /proc/iomem is used for consistency. Since my kexec-tools (for arm64)
have to access /proc/iomem to identify usable memory regions on
*UEFI* systems anyway, I didn't think it was odd.

(Please note that UEFI won't expose memory regions information via
a device tree, but via ACPI table.)

> In the case of the crashkernel reserved region, that information is in 
> /chosen/linux,crashkernel-base and /chosen/linux,crashkernel-size.
> 
> Either way is fine I think. I'm just mentioning this for reference in case 
> you want the ARM implementation to be closer to another arch which is also 
> based on the device tree.

Adding those properties to a device tree is quite easy
(and it won't conflict with /proc/iomem), so I'd like 
to defer to arm64 maintainers.

Thanks,
-Takahiro AKASHI

> -- 
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
> 

  reply	other threads:[~2016-07-07  1:12 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-06  7:52 [PATCH v21 0/8] arm64: kdump support AKASHI Takahiro
2016-07-06  7:52 ` AKASHI Takahiro
2016-07-06  7:52 ` [PATCH v21 1/8] arm64: kdump: reserve memory for crash dump kernel AKASHI Takahiro
2016-07-06  7:52   ` AKASHI Takahiro
2016-07-06 17:00   ` Geoff Levand
2016-07-06 17:00     ` Geoff Levand
2016-07-07  0:19     ` AKASHI Takahiro
2016-07-07  0:19       ` AKASHI Takahiro
2016-07-06 18:11   ` Thiago Jung Bauermann
2016-07-06 18:11     ` Thiago Jung Bauermann
2016-07-07  1:17     ` AKASHI Takahiro [this message]
2016-07-07  1:17       ` AKASHI Takahiro
2016-07-06  7:52 ` [PATCH v21 2/8] arm64: limit memory regions based on DT property, usable-memory AKASHI Takahiro
2016-07-06  7:52   ` AKASHI Takahiro
2016-07-06 17:48   ` Geoff Levand
2016-07-06 17:48     ` Geoff Levand
2016-07-06  7:52 ` [PATCH v21 3/8] arm64: kdump: implement machine_crash_shutdown() AKASHI Takahiro
2016-07-06  7:52   ` AKASHI Takahiro
2016-07-06 17:28   ` Geoff Levand
2016-07-06 17:28     ` Geoff Levand
2016-07-07  0:43     ` AKASHI Takahiro
2016-07-07  0:43       ` AKASHI Takahiro
2016-07-07 16:42       ` Geoff Levand
2016-07-07 16:42         ` Geoff Levand
2016-07-06  7:52 ` [PATCH v21 4/8] arm64: kdump: add kdump support AKASHI Takahiro
2016-07-06  7:52   ` AKASHI Takahiro
2016-07-06 17:38   ` Geoff Levand
2016-07-06 17:38     ` Geoff Levand
2016-07-07  0:49     ` AKASHI Takahiro
2016-07-07  0:49       ` AKASHI Takahiro
2016-07-06  7:52 ` [PATCH v21 5/8] arm64: kdump: add VMCOREINFO's for user-space coredump tools AKASHI Takahiro
2016-07-06  7:52   ` AKASHI Takahiro
2016-07-06  7:52 ` [PATCH v21 6/8] arm64: kdump: enable kdump in the arm64 defconfig AKASHI Takahiro
2016-07-06  7:52   ` AKASHI Takahiro
2016-07-06  7:52 ` [PATCH v21 7/8] arm64: kdump: update a kernel doc AKASHI Takahiro
2016-07-06  7:52   ` AKASHI Takahiro
2016-07-06 17:44   ` Geoff Levand
2016-07-06 17:44     ` Geoff Levand
2016-07-07  0:51     ` AKASHI Takahiro
2016-07-07  0:51       ` AKASHI Takahiro
2016-07-06  7:52 ` [PATCH v21 8/8] Documentation: dt: usable-memory and elfcorehdr nodes for arm64 kexec AKASHI Takahiro
2016-07-06  7:52   ` AKASHI Takahiro
2016-07-06 17:46   ` Geoff Levand
2016-07-06 17:46     ` Geoff Levand
2016-07-06 19:29   ` Thiago Jung Bauermann
2016-07-06 19:29     ` Thiago Jung Bauermann
2016-07-06 19:29     ` Thiago Jung Bauermann
2016-07-07  2:00     ` AKASHI Takahiro
2016-07-07  2:00       ` AKASHI Takahiro
2016-07-07  2:00       ` AKASHI Takahiro
2016-07-07 18:46       ` Thiago Jung Bauermann
2016-07-07 18:46         ` Thiago Jung Bauermann
2016-07-07 18:46         ` Thiago Jung Bauermann

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