On Mon, Sep 30, 2013 at 11:27 AM, Grant Likely <grant.likely(a)linaro.org> wrote:
> On Mon, Sep 30, 2013 at 5:46 PM, Leif Lindholm <leif.lindholm(a)linaro.org> wrote:
>> On Mon, Sep 30, 2013 at 08:05:59AM -0700, Roy Franz wrote:
>>> > I was thinking that the stub would want to use the FDT passed by grub
>>> > if one is passed, but I hadn't thought about the case where grub wants
>>> > to pass information to the stub, but the stub still loads the FDT. The
>>> > easiest thing would be to straight out say that if GRUB is loading the
>>> > initrd, then it is mandatory for GRUB to also load the FDT. That
>>> > eliminates the corner case and I can't think of any situation where
>>> > we'd want GRUB loading the initrd, but use the stub to load the FDT.
>>>
>>> I'd also like to avoid having the stub merge FDT contents from different trees.
>>>
>>> If we add this table, then it seems this would be the right way to
>>> handle passing
>>> the FDT to the EFI stub, even without GRUB involved. Is there a reason not to
>>> move to this method in general?
>>
>> Not really.
>> So ... I guess that would modify the stub behaviour to:
>> - Look for an FDT_GUID configuration table.
>> - If there, use it.
>> - If not there, require one to be loaded based on command line.
>
> Create a mostly empty one for passing freeform data to the kernel
> proper; this is what it will look like on ACPI systems.
So for ACPI systems the stub will package the ACPI data into the FDT?
What would the stub be putting into the FDT that an ACPI/UEFI aware kernel
couldn't get itself at runtime from UEFI?
>
>> And the GRUB behaviour to:
>> - If no FDT_GUID, require FDT if initrd.
>> - If FDT_GUID, copy FDT + add initrd information.
>>
>> The x86 code uses bootparam to pass the kernel command line.
>> Could we use the FDT exists) for the kernel command line
>> too? This would make more code shared between x86 and ARM*, since
>> otherwise we would need to explicitly implement (UCS?) command line
>> passing to stub?
>
> Yes, I think that makes sense. That also means GRUB will need to
> always create an FDT, even if it is empty.
I'm not following something here - why would GRUB create an empty FDT?
Is GRUB going to be responsible for the complete FDT, or just passing the
initrd and/or command line in an FDT?
>
> The other option would be to pass the command line via the LoadOptions
> from the EFI_LOADED_IMAGE protocol. I believe that is what Roy's
> patches currently rely on for getting a command line.
Yes, both my implementation and the x86 implementation get the command line
from the EFI_LOADED_IMAGE protocol, and do conversion from UCS-2 (I think)
to ASCII/UTF-8 to pass to the kernel. The format of the command line does not
seem to be specified by UEFI.
>
> g.
On Mon, Sep 30, 2013 at 07:27:58PM +0100, Grant Likely wrote:
> > So ... I guess that would modify the stub behaviour to:
> > - Look for an FDT_GUID configuration table.
> > - If there, use it.
> > - If not there, require one to be loaded based on command line.
>
> Create a mostly empty one for passing freeform data to the kernel
> proper; this is what it will look like on ACPI systems.
OK. So we push the actual error condition of missing tree down to stub?
Makes sense.
> > The x86 code uses bootparam to pass the kernel command line.
> > Could we use the FDT exists) for the kernel command line
> > too? This would make more code shared between x86 and ARM*, since
> > otherwise we would need to explicitly implement (UCS?) command line
> > passing to stub?
>
> Yes, I think that makes sense. That also means GRUB will need to
> always create an FDT, even if it is empty.
Yes. This would be my preference.
> The other option would be to pass the command line via the LoadOptions
> from the EFI_LOADED_IMAGE protocol. I believe that is what Roy's
> patches currently rely on for getting a command line.
Since the current code doesn't UEFI-wise "load" the stub image, we'd
effectively need to reverse-reconstruct GRUB's runtime environment,
which I really wouldn't like.
/
Leif
On Mon, Sep 30, 2013 at 7:51 AM, Grant Likely <grant.likely(a)linaro.org> wrote:
> On Mon, Sep 30, 2013 at 2:59 PM, Leif Lindholm <leif.lindholm(a)linaro.org> wrote:
>> Hi guys,
>>
>> I've been looking at the patches Matthew Garrett wrote for loading a
>> UEFI stub kernel through GRUB, and noticed one thing that may require
>> updates to the stub code: it uses GRUB to load the initrd.
>> Doing this of course means the initrd does not need to go into the EFI
>> System Partition, which is a lot nicer from the distros' position.
>>
>> Now, in x86 land GRUB just passes the stub a bootparam structure, and
>> I assume it just keeps filling the same structure in before passing it
>> on to the kernel .
>>
>> On ARM*, we would need to get this information over "some other way",
>> where the obvious candidate would be FDT.
>>
>> GRUB could register an empty devicetree, with only the initrd
>> information in it, as a UEFI configuration table. (Getting a UUID for
>> this was discussed in New Orleans.)
>
> Right. It would be a trivial feature to have a UUID in the system
> table pointing to an allocated block of memory containing an FDT. It
> would also be nice to give the FDT some extra space when loaded so
> that the libfdt functions can work in-place... but I digress; the flat
> tree structure already contains enough information to do that.
>
>> Or, on systems using FDT for hardware description, once firmware
>> becomes mature enough to do this themselves - add this information to
>> the system-provided one.
>>
>> The stub would then need to look for this devicetree, and if present,
>> copy the initrd nodes across into the one it loads itself.
>
> I was thinking that the stub would want to use the FDT passed by grub
> if one is passed, but I hadn't thought about the case where grub wants
> to pass information to the stub, but the stub still loads the FDT. The
> easiest thing would be to straight out say that if GRUB is loading the
> initrd, then it is mandatory for GRUB to also load the FDT. That
> eliminates the corner case and I can't think of any situation where
> we'd want GRUB loading the initrd, but use the stub to load the FDT.
I'd also like to avoid having the stub merge FDT contents from different trees.
If we add this table, then it seems this would be the right way to
handle passing
the FDT to the EFI stub, even without GRUB involved. Is there a reason not to
move to this method in general?
>
>> Alternatively, we could define a special protocol for passing
>> additional parameters to the stubbed kernel ... or a special protocol
>> to pass a special FDT but I'm not sure we want yet another interface.
>
> Indeed. I definitely don't want to do this.
Agreed...
>
> g.
Hi guys,
I've been looking at the patches Matthew Garrett wrote for loading a
UEFI stub kernel through GRUB, and noticed one thing that may require
updates to the stub code: it uses GRUB to load the initrd.
Doing this of course means the initrd does not need to go into the EFI
System Partition, which is a lot nicer from the distros' position.
Now, in x86 land GRUB just passes the stub a bootparam structure, and
I assume it just keeps filling the same structure in before passing it
on to the kernel .
On ARM*, we would need to get this information over "some other way",
where the obvious candidate would be FDT.
GRUB could register an empty devicetree, with only the initrd
information in it, as a UEFI configuration table. (Getting a UUID for
this was discussed in New Orleans.)
Or, on systems using FDT for hardware description, once firmware
becomes mature enough to do this themselves - add this information to
the system-provided one.
The stub would then need to look for this devicetree, and if present,
copy the initrd nodes across into the one it loads itself.
Alternatively, we could define a special protocol for passing
additional parameters to the stubbed kernel ... or a special protocol
to pass a special FDT but I'm not sure we want yet another interface.
Thoughts?
/
Leif
Hi all,
The uefi-next.git tree [1] has been updated for the 13.09 cycle.
We're at -rc1, but the code freeze is today, so probably not enough time
for any changes before the release.
Snapshot binaries are available now [2]
What's included?
Well, not as much as I hoped because I've run out of time. So no ethernet
and no SMBIOS patches just yet.
Current topic branches:
linaro-topic-a5
linaro-topic-a9
linaro-topic-arndale
linaro-topic-bds
linaro-topic-fvp
linaro-topic-misc
linaro-topic-origen
linaro-topic-panda
linaro-topic-tc1
linaro-topic-tc2
As always, you should probably pull and build the "linaro-tracking" branch,
not one of the topic branches.
The main addition for this release is the (now) upstream aarch64 support.
The uefi_rtsm-ve-aemv8.bin snapshot binary will boot on the Aarch64 VE
model that is currently available to Linaro internal people from the usual
place [4]
I've tested A9, TC2, FVP on the snapshot binaries. I tested RTSMs, aarch64
VE model and Arndale on my own build of the code and Dave Long has tested
Panda on his own build of the same code.
One problem I note for aarch64 is that we don't have a similar fix to this
for native building:
4511a19 2012-12-12 BaseTools: allow native building [Leif Lindholm]
Probably not a big issue, who would want to compile aarch64 inside a model??
Regards,
Ryan.
[1] https://git.linaro.org/gitweb?p=arm/uefi/uefi-next.git;a=summary
[2] https://snapshots.linaro.org/components/kernel/uefi-next/152
[3]
https://snapshots.linaro.org/components/kernel/uefi-next/152/uefi_rtsm-ve-a…
[4] https://collaborate.linaro.org/display/ITS/FlexLM+and+Fast+Models
Hi,
I have checked out to the 2012.09.1 branch of the
u-boot-linaro-stable source and built the u-boot for panda. It worked
fine. Then I enabled the Debug prints and again built the u-boot. But
this time the u-boot hanged up in the middle. In my observations, it
hanged up at the end of the board_init_f() function in the
arch/arm/lib/board.c. At the end it has the relocate_code() function
that might cause the problem. Im stuck up with this and any help would
be appreciated.
Thanks,
Davidson. K
Hi,
a normal Linux kernel currently supports reading the start and end
address of a single binary blob via the FDT's /chosen node.
This will be interpreted as the location of an initial RAM disk.
The Xen hypervisor itself is a kernel, but needs up to _two_ binaries
for proper operation: a Dom0 Linux kernel and it's associated initrd.
On x86 this is solved via the multiboot protocol used by the Grub
bootloader, which supports to pass an arbitrary number of binary modules
to any kernel.
Since in the ARM world we have the versatile device tree, we don't need
to implement the mulitboot protocol.
So I'd like to propose a new binding which denotes binary modules a
kernel can use at it's own discretion.
The need is triggered by the Xen hypervisor (which already uses a very
similar scheme), but the approach is deliberately chosen to be as
generic as possible to allow future uses (like passing firmware blobs
for devices or the like).
Credits for this go to Ian Campbell, who started something very similar
[1] for the Xen hypervisor. The intention of this proposal is to make
this generic and publicly documented.
Looking forward to any comments!
Thanks,
Andre.
[1]
http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=docs/misc/arm/device-tree…
----------------------------
* Multiple boot modules device tree bindings
Boot loaders wanting to pass multiple additional binaries to a kernel
shall add a node "module" for each binary blob under the /chosen node
with the following properties:
- compatible:
compatible = "boot,module";
A bootloader may add names to more specifically describe the module,
e.g. Xen may use "xen,dom0-kernel" or "xen,dom0-ramdisk".
If possible a kernel should be able to use modules even without a
descriptive naming, by enumerating them in order and using hard-coded
meanings for each module (e.g. first is kernel, second is initrd).
- reg: specifies the base physical address and size of a region in
memory where the bootloader loaded the respective binary data to.
- bootargs:
An optional property describing arguments to use for this module.
Could be a command line or configuration data.
Example:
/chosen {
#size-cells = <0x1>;
#address-cells = <0x1>;
module@0 {
compatible = "xen,linux-zimage", "xen,multiboot-module",
"boot,module";
reg = <0x80000000 0x003dcff8>;
bootargs = "console=hvc0 earlyprintk ro root=/dev/sda1 nosmp";
};
module@1 {
compatible = "xen,linux-initrd", "xen,multiboot-module",
"boot,module";
reg = <0x08000000 0x00123456>;
};
...