On 01/20/2012 02:47 AM, Peter Maydell wrote:
> On 19 January 2012 23:17, Rob Herring <[email protected]> wrote:
>> On 01/19/2012 03:44 PM, Peter Maydell wrote:
>>> On 19 January 2012 21:31, Mark Langsdorf <[email protected]> wrote:
>>>> + highbank_binfo.board_id = 0xEC10100f; /* provided by deviceTree */
>>>
>>> Where does this number come from? It's not in
>>> http://www.arm.linux.org.uk/developer/machines/
>>>
>>> Is 3027 (==0xbd3) you?
>>> http://www.arm.linux.org.uk/developer/machines/list.php?id=3027
>>>
>>
>> Much of the data there is wrong as none of it is used. 0 or -1 is the
>> right value as those are obviously meaningless. A highbank kernel will
>> never be booted without devicetree and in that case this number is
>> irrelevant. This is the legacy boot interface and qemu really needs to
>> learn to boot with a separate dtb.
>
> Yeah, but the documentation even for DTB boot says we should pass
> in a machine number. If 0 or -1 are right then there should be
> some documentation that says so. I'll accept "mailing list post
> from some authoritative person [eg Grant Likely]" if necessary.
Kernel DT co-maintainer is not authoritative enough for you?
The documentation needs some clarification.
> But this is an ABI between boot loaders and the kernel so I don't
> want to just have something random that happens to work. (And in
> particular if -1 is the officially sanctioned number then we need
> to fix arm_boot to be able to pass values >16 bits wide.)
>
Here's were the kernel sets the mach #. nr is from the database for
non-DT and ~0 for DT machines.
#define MACHINE_START(_type,_name) \
static const struct machine_desc __mach_desc_##_type \
__used \
__attribute__((__section__(".arch.info.init"))) = { \
.nr = MACH_TYPE_##_type, \
.name = _name,
#define MACHINE_END \
};
#define DT_MACHINE_START(_name, _namestr) \
static const struct machine_desc __mach_desc_##_name \
__used \
__attribute__((__section__(".arch.info.init"))) = { \
.nr = ~0, \
.name = _namestr,
In any case, the kernel ignores the value passed in if a valid dtb is
passed in.
Rob
