Hi Andrew, On 5 May 2017 at 17:01, Andrew Cooper <andrew.coop...@citrix.com> wrote: > On 05/05/17 09:57, Fu Wei wrote: >> Hi Stefano, >> >> On 4 May 2017 at 04:53, Stefano Stabellini <sstabell...@kernel.org> wrote: >>> On Wed, 3 May 2017, Andrew Cooper wrote: >>>> On 02/05/17 08:06, fu....@linaro.org wrote: >>>>> From: Fu Wei <fu....@linaro.org> >>>>> >>>>> This patch adds the support of xen_boot command for aarch64: >>>>> xen_hypervisor >>>>> xen_module >>>>> These two commands are only for aarch64, since it has its own protocol and >>>>> commands to boot xen hypervisor and Dom0, but not multiboot. >>>>> >>>>> For other architectures, they are still using multiboot and module >>>>> commands. >>>>> >>>>> Signed-off-by: Fu Wei <fu....@linaro.org> >>>> Sorry if I am jumping in late and asking awkward questions, but what is >>>> special about Xen/aarch64 here? Why is it using a non-standard entry >>>> mechanism? >>> Multiboot is not available on ARM. The boot protocol we have on ARM is >>> FDT based: >>> >>> http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=docs/misc/arm/device-tree/booting.txt >>> >>> We often refer to it as "multiboot for arm" but in fact it is not >>> related to the x86 multiboot in any way. >>> >>> In Grub, the two protocols (multiboot and >>> docs/misc/arm/device-tree/booting.txt) are kept clearly distinct >>> (55a687e5.4070...@gmail.com). Hence, the need for this patch. >> Exactly, great thanks for your explanation! :-) > > So it really is an entirely custom Xen booting protocol.
Yes, it is. > > It is unfortunate that this wasn't reviewed sensibly at the time (and > implemented in a project-neutral way), but it looks like the time to fix > that properly has long since passed. I guess the reason Xen use an entirely custom(lightweight) booting protocol on aarch64 is that the multiboot maybe a little "heavy" for aarch64. > > ~Andrew -- Best regards, Fu Wei Software Engineer Red Hat _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
