Grant Likely wrote:
(cc'ing devicetree-discuss and others)
On Sun, May 23, 2010 at 5:32 PM, Nigel Cunningham
<[email protected]> wrote:
http://elinux.org/CELF_Project_Proposal/Add_Device_Tree_emulation_support_to_QEMU
Just in case anyone is interested -
One Laptop Per Child is doing some ARM work, so I have resurrected
FirmWorks' ARM version of Open Firmware. It's in the open source OFW
tree at http://openfirmware.info/Open_Firmware . There is a build that
runs under QEMU, in the subdirectory cpu/arm/versatilepb . FirmWorks'
core ARM stuff is fairly solid, having been developed to shipping
quality for Digital's "Shark" (aka DNARD) system, just prior to
Digital's demise and the sale of StrongARM to Intel.
I'll be adding more elaborations in the near future. One item on the
short list is to auto-generate a flattened device tree from the real
device tree. It's a pity that the dynamic device tree has to be
projected onto a static structure, but I guess that Gresham's Law
applies to software too.
Grant, I've joined the devicetree-discuss mailing list, and am seeking to
get up to speed with things, but want to find out before I get too carried
away what your thoughts are on Rob's proposal. In your opinion, is there a
useful contribution I can make in this area, or do you already have it all
in hand and not need any help? (I'm not sure how old Rob's proposal is).
Hi Nigel,
A bunch of work has already been done in this area, but not all of it
has been pushed upstream. Edgar Ingesias and John Williams
collaborated to bring up QEMU microblaze support, including a device
tree parser. I believe John & Petalogix is continuing to pursue this
work, but I don't know what the state of it is. Much of the
Microblaze support is in mainline, but I don't think the device tree
parser has been pushed up yet. John and Edgar can tell you about this
much better than I.
Independently, Jeremy Kerr added QEMU support for passing a device
tree to the kernel on the ARM architecture via an ATAG, and I added
code for generating the device tree contents from the set of
instantiated devices. This approach is rather different from what
John and Edgar have done as it still requires a separate method of
configuring QEMU. While I find it useful, this approach probably
isn't the best long term solution.
I'm not actively working on this other than adding the bits and pieces
I need to improve the ARM device tree support in the kernel. You'll
have to coordinate with John and Edgar to figure out if there is a
useful contribution that you can make.
Cheers,
g.
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