On Mon, Sep 30, 2013 at 10:28:49PM +0100, Grant Likely wrote:
> > > load image protocol. In that case the sub should override the setting in
> the
> > > FDT if the initrd argument is present.
> >
> > Hmm, well, it's slightly worse than that - it will have one; only it
> > will be GRUB's command line.
> >
> > The way that can be resolved is:
> > - FDT present?
> > - Commandline present in FDT chosen node?
> > - Yes
> > - Use that.
> > - No
> > - EFI_LOADED_IMAGE command line present?
> > - Yes
> > - Use that.
> > - No
> > - Fail miserably.
> That doesn't handle the case where firmware provides the fdt, but the kernel is
> loaded via the UEFI shell or gummiboot. In that case the stub must process both
> the loaded image arguments.
Well, unless the firmware-provided device tree contains a kernel
command line, that should work fine?
If you mean that there are two command lines to parse for the
EFI_LOADED_IMAGE (one for shell/gummiboot), surely there is a handle
in there to identify the "current" one.
/
Leif
On Mon, Sep 30, 2013 at 09:05:04PM +0100, Grant Likely wrote:
> > Handling the 2 cases is not a problem. I just don't want to handle
> > 'mixed' cases where
> > a command line and an FDT are passed to the stub, and information from
> > both is used.
> >
> > As I understand it, the two cases are:
> >
> > FDT_GUID present == GRUB case
> > * GRUB loads initrd if present
> > * GRUB provides complete FDT to stub (includes command line, hardware
> > description, initrd entry, etc.)
> > * EFI stub loads FDT using FDT_GUID, adds memory map and system table
> > pointer to FDT, starts kernel.
> > * (any command line present in EFI_LOADED_IMAGE is ignored.)
> >
> > FDT_GUID absent == current case
> > * stub loads FDT and initrd from system partition
> > * stub adds command line from EFI_LOADED_IMAGE to FDT
> > * stub adds initrd entry to FDT
> > * stub adds memory map and system table pointer to FDT, starts kernel.
> >
> > In the case of UEFI owning the FDT, and providing it to the stub,
> > where does the initrd come from? I think this adds
> > another case to handle...
> The stub will still need to process a command line if it is given one via the
> load image protocol. In that case the sub should override the setting in the
> FDT if the initrd argument is present.
Hmm, well, it's slightly worse than that - it will have one; only it
will be GRUB's command line.
The way that can be resolved is:
- FDT present?
- Commandline present in FDT chosen node?
- Yes
- Use that.
- No
- EFI_LOADED_IMAGE command line present?
- Yes
- Use that.
- No
- Fail miserably.
/
Leif
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