Re: [Xen-devel] [PATCH] ARM/multiboot: use more flexible node naming

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2013-09-05 at 15:54 +0200, Egger, Christoph wrote:
> Is there a chance to get NetBSD Dom0 [1] to boot to justify that your
> approach is *really* generic.
> 
> xen,linux-zimage and xen,linux-initrd do not sound generic
> but xen,dom0-kernel and xen,ramdisk do sound generic at least.

Does NetBSD follow the Linux zImage boot protocol
(Documentation/arm/Booting.txt in a Linux source tree)?

If not then you need to define (or link to) the NetBSD boot protocol and
we probably will eventually need xen,netbsd-fooimg and suitable code in
Xen to handle that format.

> [1] NetBSD Dom0 hasn't been ported to ARM yet.

So surely you have answered your own question then, unless you are
asking Andre to port NetBSD to ARM? I don't think that is a reasonable
prerequisite for this patch.

> 
> 
> On 05.09.13 15:43, Andre Przywara wrote:
> > For the current "multiboot" on ARM support we look for a compatible
> > string of "xen,multiboot-module" in the device tree, and then
> > use "xen,linux-zimage" and "xen,linux-initrd" to differentiate
> > between the two supported module types.
> > To meet the more generic multiboot proposal in the device tree [1],
> > allow Xen to be more flexible in the compatible naming and also use
> > the new generic base name "boot,module".
> > The mapping to either Dom0 kernel or RAM disk works either by
> > providing a more specific name ("xen,dom0-kernel" and "xen,ramdisk"),
> > or by using the enumeration order of the device tree nodes
> > (module@0 = kernel, module@1 = initrd). This allows bootloaders
> > without any specific Xen knowledge to boot Xen anyways.
> > 
> > [1] http://lists.xen.org/archives/html/xen-devel/2013-09/msg00083.html
> > 
> > Signed-off-by: Andre Przywara <andre.przywara@xxxxxxxxxx>
> > ---
> >  xen/common/device_tree.c | 57 
> > ++++++++++++++++++++++++++++++++++++++++++------
> >  1 file changed, 50 insertions(+), 7 deletions(-)
> > 
> > diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
> > index ec0d5e2..e10c035 100644
> > --- a/xen/common/device_tree.c
> > +++ b/xen/common/device_tree.c
> > @@ -439,22 +439,63 @@ static void __init process_cpu_node(const void *fdt, 
> > int node,
> >      cpumask_set_cpu(start, &cpu_possible_map);
> >  }
> >  
> > +static const char * const kernel_module_names[] = {
> > +   "xen,linux-zimage",
> > +   "xen,dom0-kernel",
> > +   "boot,kernel",
> > +   NULL
> > +};
> > +
> > +static const char * const initrd_module_names[] = {
> > +   "xen,linux-initrd",
> > +   "xen,ramdisk",
> > +   "boot,ramdisk",
> > +   NULL
> > +};
> > +
> >  static void __init process_multiboot_node(const void *fdt, int node,
> >                                            const char *name,
> >                                            u32 address_cells, u32 
> > size_cells)
> >  {
> >      const struct fdt_property *prop;
> >      const u32 *cell;
> > -    int nr;
> > +    int nr = -1;
> >      struct dt_mb_module *mod;
> >      int len;
> > +    const char* const * name_list;
> >  
> > -    if ( fdt_node_check_compatible(fdt, node, "xen,linux-zimage") == 0 )
> > -        nr = MOD_KERNEL;
> > -    else if ( fdt_node_check_compatible(fdt, node, "xen,linux-initrd") == 
> > 0)
> > -        nr = MOD_INITRD;
> > -    else
> > -        early_panic("%s not a known xen multiboot type\n", name);
> > +    for (name_list = kernel_module_names; *name_list != NULL; name_list++)
> > +        if ( fdt_node_check_compatible(fdt, node, *name_list) == 0 ) {
> > +            nr = MOD_KERNEL;
> > +            break;
> > +        }
> > +
> > +    for (name_list = initrd_module_names; *name_list != NULL; name_list++)
> > +        if ( fdt_node_check_compatible(fdt, node, *name_list) == 0 ) {
> > +            nr = MOD_INITRD;
> > +            break;
> > +        }
> > +
> > +    if (nr == -1) {
> > +           char *s;
> > +
> > +        if ( fdt_node_check_compatible(fdt, node, "boot,module") != 0 ) {
> > +            early_panic("%s not a known xen multiboot type\n", name);
> > +            return;
> > +        }
> > +        s = strchr(name, '@');
> > +        if (s == NULL)
> > +            nr = early_info.modules.nr_mods + 1;
> > +        else {
> > +            nr = simple_strtoll(s + 1, NULL, 10) + 1;
> > +        }
> > +    }
> > +
> > +    if (nr >= NR_MODULES) {
> > +        early_panic("only supporting %d multiboot modules\n",
> > +            NR_MODULES - MOD_DISCARD_FIRST);
> > +        return;
> > +    }
> >  
> >      mod = &early_info.modules.module[nr];
> >  
> > @@ -492,6 +533,8 @@ static int __init early_scan_node(const void *fdt,
> >          process_cpu_node(fdt, node, name, address_cells, size_cells);
> >      else if ( device_tree_node_compatible(fdt, node, 
> > "xen,multiboot-module" ) )
> >          process_multiboot_node(fdt, node, name, address_cells, size_cells);
> > +    else if ( device_tree_node_compatible(fdt, node, "boot,module" ) )
> > +        process_multiboot_node(fdt, node, name, address_cells, size_cells);
> >  
> >      return 0;
> >  }
> > 
> 



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