From: Dave Young <dyoung@redhat.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
bhe@redhat.com, kexec@lists.infradead.org,
linux-kernel@vger.kernel.org, Vivek Goyal <vgoyal@redhat.com>,
AKASHI Takahiro <takahiro.akashi@linaro.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
bauerman@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC 0/3] extend kexec_file_load system call
Date: Thu, 14 Jul 2016 09:50:27 +0800 [thread overview]
Message-ID: <20160714015027.GA3121@dhcp-128-65.nay.redhat.com> (raw)
In-Reply-To: <20160713093432.GB14522@leverpostej>
On 07/13/16 at 10:34am, Mark Rutland wrote:
> On Wed, Jul 13, 2016 at 10:36:14AM +0800, Dave Young wrote:
> > But consider we can kexec to a different kernel and a different initrd so there
> > will be use cases to pass a total different dtb as well.
>
> It depends on what you mean by "a different kernel", and what this
> implies for the DTB.
>
I thought about kexec as a boot loader just like other bootloaders.
So just like a normal boot kexec should also accept external dtb.
But acutally kexec is different because it can get original dtb and
use it. So I agreed if we can not find a real use case that we have
to extend it we should keep current interface.
> I expect future arm64 Linux kernels to function with today's DTBs, and
> the existing boot protocol. The kexec_file_load syscall already has
> enough information for the kernel to inject the initrd and bootargs
> properties into a DTB.
>
> In practice on x86 today, kexec_file_load only supports booting to a
> Linux kernel, because the in-kernel purgatory only implements the x86
> Linux boot protocol. Analagously, for arm64 I think that the first
> kernel should use its internal copy of the boot DTB, with /chosen fixed
> up appropriately, assuming the next kernel is an arm64 Linux image.
>
> If booting another OS, the only parts of the DTB I would expect to
> change are the properties under chosen, as everything else *should* be
> OS-independent. However the other OS may have a completely different
> boot protocol, might not even take a DTB, and will likely need a
> compeltely different purgatory implementation. So just allowing the DTB
> to be altered isn't sufficient for that case.
>
> There might be cases where we want a different DTB, but as far as I can
> tell we have nothing analagous on x86 today. If we do need this, we
> should have an idea of what real case(s) were trying to solve.
Agreed.
Thanks
Dave
next prev parent reply other threads:[~2016-07-14 1:50 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-12 1:41 [RFC 0/3] extend kexec_file_load system call AKASHI Takahiro
2016-07-12 1:41 ` [RFC 1/3] syscall: add kexec_file_load to generic unistd.h AKASHI Takahiro
2016-07-12 1:42 ` [RFC 2/3] kexec: add dtb info to struct kimage AKASHI Takahiro
2016-07-12 1:42 ` [RFC 3/3] kexec: extend kexec_file_load system call AKASHI Takahiro
2016-07-15 13:09 ` Vivek Goyal
2016-07-15 13:19 ` Mark Rutland
2016-07-18 2:30 ` Dave Young
2016-07-18 10:07 ` Mark Rutland
2016-07-19 0:55 ` Dave Young
2016-07-19 10:52 ` Mark Rutland
2016-07-19 12:24 ` Vivek Goyal
2016-07-19 12:47 ` Mark Rutland
2016-07-19 13:26 ` Vivek Goyal
2016-07-20 11:41 ` David Laight
2016-07-21 9:21 ` Russell King - ARM Linux
2016-07-18 2:33 ` Dave Young
2016-07-27 0:24 ` [PATCH v2 " Thiago Jung Bauermann
2016-08-05 20:46 ` Thiago Jung Bauermann
2016-07-12 13:25 ` [RFC 0/3] " Eric W. Biederman
2016-07-12 13:58 ` Thiago Jung Bauermann
2016-07-12 14:02 ` Vivek Goyal
2016-07-12 23:45 ` Stewart Smith
2016-07-13 13:27 ` Vivek Goyal
2016-07-12 14:02 ` Arnd Bergmann
2016-07-12 14:18 ` Vivek Goyal
2016-07-12 14:24 ` Arnd Bergmann
2016-07-12 14:50 ` Mark Rutland
2016-07-13 2:36 ` Dave Young
2016-07-13 8:01 ` Arnd Bergmann
2016-07-13 8:23 ` Stewart Smith
2016-07-13 9:41 ` Mark Rutland
2016-07-13 13:13 ` Arnd Bergmann
2016-07-13 18:45 ` Thiago Jung Bauermann
2016-07-13 19:59 ` Arnd Bergmann
2016-07-14 2:18 ` Thiago Jung Bauermann
2016-07-14 8:29 ` Arnd Bergmann
2016-07-15 1:44 ` Thiago Jung Bauermann
2016-07-15 7:31 ` Arnd Bergmann
2016-07-15 13:26 ` Vivek Goyal
2016-07-15 13:33 ` Mark Rutland
2016-07-15 15:29 ` Thiago Jung Bauermann
2016-07-15 15:47 ` Mark Rutland
2016-07-15 13:42 ` Russell King - ARM Linux
2016-07-15 20:26 ` Arnd Bergmann
2016-07-15 21:03 ` Thiago Jung Bauermann
2016-07-22 0:09 ` Thiago Jung Bauermann
2016-07-22 0:53 ` Jeremy Kerr
2016-07-22 2:54 ` Michael Ellerman
2016-07-22 20:41 ` Thiago Jung Bauermann
2016-07-15 8:49 ` Russell King - ARM Linux
2016-07-15 13:03 ` Vivek Goyal
2016-07-13 9:34 ` Mark Rutland
2016-07-13 17:38 ` AKASHI Takahiro
2016-07-13 17:58 ` Mark Rutland
2016-07-13 19:57 ` Arnd Bergmann
2016-07-14 12:42 ` Mark Rutland
2016-07-14 1:54 ` Dave Young
2016-07-14 1:50 ` Dave Young [this message]
2016-07-12 16:25 ` Thiago Jung Bauermann
2016-07-12 20:58 ` Petr Tesarik
2016-07-12 21:22 ` Eric W. Biederman
2016-07-12 21:36 ` Eric W. Biederman
2016-07-12 21:53 ` Petr Tesarik
2016-07-12 22:18 ` Russell King - ARM Linux
2016-07-13 4:59 ` Stewart Smith
2016-07-13 7:36 ` Russell King - ARM Linux
2016-07-13 7:47 ` Ard Biesheuvel
2016-07-13 8:09 ` Russell King - ARM Linux
2016-07-13 8:20 ` Stewart Smith
2016-07-13 7:55 ` Stewart Smith
2016-07-13 8:26 ` Russell King - ARM Linux
2016-07-13 8:36 ` Dave Young
2016-07-13 8:57 ` Petr Tesarik
2016-07-13 13:03 ` Vivek Goyal
2016-07-13 17:40 ` Russell King - ARM Linux
2016-07-13 18:22 ` Vivek Goyal
2016-07-18 12:46 ` Balbir Singh
2016-07-18 13:26 ` Vivek Goyal
2016-07-18 13:38 ` Vivek Goyal
2016-07-20 3:45 ` Balbir Singh
2016-07-20 8:35 ` Russell King - ARM Linux
2016-07-20 11:12 ` Arnd Bergmann
2016-07-20 15:50 ` Thiago Jung Bauermann
2016-07-20 12:46 ` Vivek Goyal
2016-07-20 12:27 ` Vivek Goyal
2016-07-12 23:41 ` Stewart Smith
2016-07-13 13:25 ` Vivek Goyal
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