From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: From: Arnd Bergmann Subject: Re: [RFC 0/3] extend kexec_file_load system call Date: Wed, 13 Jul 2016 21:57:28 +0200 Message-ID: <7927804.6bj1abO0d2@wuerfel> In-Reply-To: <20160713175630.GA2668@leverpostej> References: <20160712014201.11456-1-takahiro.akashi@linaro.org> <20160713173804.GA25723@porco> <20160713175630.GA2668@leverpostej> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Mark Rutland Cc: linux-arm-kernel@lists.infradead.org, bhe@redhat.com, linuxppc-dev@lists.ozlabs.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, AKASHI Takahiro , "Eric W. Biederman" , bauerman@linux.vnet.ibm.com, Dave Young , Vivek Goyal On Wednesday, July 13, 2016 6:58:32 PM CEST Mark Rutland wrote: > > > we may want to remove unnecessary devices and even add a dedicated > > storage device for storing a core dump image. > > I suspect that bringing up a minimal number of devices is better > controlled by a cmdline option. In general, figuring out what is > necessary and what is not is going to be board specific, so hacking the > FW tables (DTB or ACPI) is not a very portable/reliable approach. > > Do we actually add devices in practice? More so than the above that > requires special knowledge of the platform (including things that were > not described in the boot DTB). > > In the ACPI case modifying a DTB alone is not sufficient to change the > information regarding devices, as those won't be described in the DTB. > It's not possible to convert ACPI to DTB in general. A more likely scenario would be replacing ACPI tables with a DTB that describes the platform in order to use devices that the ACPI tables don't contain. > > - Say, booting BE kernel on ACPI LE kernel > > In this case, there is no useful dtb in the kernel. > If the platform only has ACPI, then you cannot boot a BE kernel to begin > with. As above one cannot convert ACPI to DTB, so one would need > extensive platform knowledge for this to work. I think what he meant was to pass a DTB to the kexec kernel in order to run BE, while the original kernel can only run LE due to ACPI. If you boot a LE kernel using DTB, the same DTB should work for a kexec boot for a BE kernel. Arnd _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec