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From: ebiederm@xmission.com (Eric W. Biederman)
References: <b0443908-e36f-9bc4-4a8a-4206cb782d4b@arm.com>
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 <20200410121013.03b609fd572504c03a666f4a@linux-foundation.org>
 <20200411034414.GH2129@MiWiFi-R3L-srv>
 <20200411093009.GH25745@shell.armlinux.org.uk>
 <20200412053507.GA4247@MiWiFi-R3L-srv>
 <20200412080836.GM25745@shell.armlinux.org.uk>
Date: Sun, 12 Apr 2020 14:52:47 -0500
In-Reply-To: <20200412080836.GM25745@shell.armlinux.org.uk> (Russell King's
 message of "Sun, 12 Apr 2020 09:08:36 +0100")
Message-ID: <87wo6klbw0.fsf@x220.int.ebiederm.org>
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Subject: Re: [PATCH 1/3] kexec: Prevent removal of memory in use by a loaded
 kexec image
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To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Baoquan He <bhe@redhat.com>, David Hildenbrand <david@redhat.com>, Catalin Marinas <catalin.marinas@arm.com>, Bhupesh Sharma <bhsharma@redhat.com>, Anshuman Khandual <anshuman.khandual@arm.com>, kexec@lists.infradead.org, linux-mm@kvack.org, James Morse <james.morse@arm.com>, Andrew Morton <akpm@linux-foundation.org>, Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org


The only benefit of kexec_file_load is that it is simple enough from a
kernel perspective that signatures can be checked.

kexec_load in every other respect is the more capable and functional
interface.  It makes no sense to get rid of it.

It does make sense to reload with a loaded kernel on memory hotplug.
That is simple and easy.  If we are going to handle something in the
kernel it should simple an automated unloading of the kernel on memory
hotplug.


I think it would be irresponsible to deprecate kexec_load on any
platform.

I also suspect that kexec_file_load could be taught to copy the dtb
on arm32 if someone wants to deal with signatures.

We definitely can not even think of deprecating kexec_load until
architecture that supports it also supports kexec_file_load and everyone
is happy with that interface.  That is Linus's no regression rule.


Eric

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