On 06/05/2014 05:55 PM, Ian Campbell wrote:
On Thu, 2014-06-05 at 17:36 +0100, Julien Grall wrote:
Hi Ian,
On 06/05/2014 12:56 PM, Ian Campbell wrote:
On Thu, 2014-06-05 at 15:46 +0800, Fu Wei wrote:
I can see why you did this (it's what Xen actually supports today) but I wonder if in the interests of reducing the special cases I should create a Xen patch which causes it to accept both names so that you can just implement the "multiboot,*" stuff in common code without the special cases? (Although that depends on the reason for the other non-compat string special cases too)
I think the "multiboot,*" stuff will be better, once Xen supports this, I will update this code.
I've only compile tested this, but I *think* this does the right thing.
Ian.
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From d0acce53a086869420c2d8870d1a8a058013d6b5 Mon Sep 17 00:00:00 2001 From: Ian Campbell ian.campbell@citrix.com Date: Wed, 4 Jun 2014 18:17:10 +0100 Subject: [PATCH] xen: arm: implement generic multiboot compatibility strings
This causes Xen to accept the more generic names originally proposed by Andre in http://thread.gmane.org/gmane.linux.linaro.announce.boot/326 and incorporated into the proposal in http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions/Multiboot
This will allow bootloaders to not special case Xen (or at least to reduce the amount which is required).
Signed-off-by: Ian Campbell ian.campbell@citrix.com
xen/common/device_tree.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c index f0b17a3..5040097 100644 --- a/xen/common/device_tree.c +++ b/xen/common/device_tree.c @@ -338,9 +338,11 @@ static void __init process_multiboot_node(const void *fdt, int node, struct dt_mb_module *mod; int len;
- if ( fdt_node_check_compatible(fdt, node, "xen,linux-zimage") == 0 )
- if ( fdt_node_check_compatible(fdt, node, "xen,linux-zimage") == 0 ||
fdt_node_check_compatible(fdt, node, "multiboot,linux-zimage") == 0 )While we are modifying the protocol, "linux-zImage" is confusing in the name. Actually we can use it for an ELF, another OS... I don't think Xen will change his behavior depending of the DOM0 image.
zImage defines the boot protocol to use. Since the protocol is defined by Linux as zImage I think that is the appropriate name, if some other OS wants to mimic Linux then fine. But if we end up supporting some OS with its own boot protocol which doesn't match Linux's then that should have a distinct name of its own.
zImage is the boot protocol for arm32, this is different for arm64. Here we are talking about the protocol for dom0, why the bootloader is involved in it?
How the interface will be exposed by grub to the user? Is it the "multiboot ..." line like in x86? If so, how grub will choose what is the boot protocol for the guest?
The "ELF boot protocol" is as yet undefined. It may or may not end up resembling zImage. In any case it will be a standard made up entirely by us and as such xen-elf or something would be the correct name (unless it happens to match zImage).
IHMO, the bootloader should only give the kernel blob to the hypervisor. Then it will decide what is the best protocol to use for booting dom0.
Regards,