[U-Boot] [PATCH 1/1] efi_loader: use built-in device tree in bootefi command

[Alexander Graf]

On 22.01.18 19:43, Heinrich Schuchardt wrote:
> 
> 
> On 01/22/2018 02:59 PM, Alexander Graf wrote:
>> On 01/20/2018 01:56 PM, Heinrich Schuchardt wrote:
>>> The bootefi command has two parameters: the address of the executable
>>> and
>>> the address of the flattened device tree.
>>>
>>> When executing the devicetree command in grub this command can only
>>> replace an existing device tree. So we always want to pass a device
>>> tree.
>>>
>>> With the patch the device tree defaults to the internal one. But of
>>> cause
>>> the user still can supply his one via the second parameter.
>>>
>>> One use case is booting via iPXE from an iSCSI drive. As we may be able
>>> to choose between different operating systems in the iPXE menu we cannot
>>> know the correct device tree when invoking bootefi. The dtb might not
>>> even
>>> be installed on a local device.
>>>
>>> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
>>
>> All of this logic is already implemented in the distro boot script, so
>> if you load your iPXE EFI binary via dhcp boot, from a block device or
>> something similar, it will by default already get $fdtcontroladdr
>> passed in. I'm not sure I'm terribly happy to have additional magic in
>> the bootefi command. If you want to spawn an EFI binary without device
>> tree table, you should be able to do so IMHO.
> 
> Booting via DHCP is most insecure. Neither the client nor the server are
> authenticated.
> 
> My understanding is that ftd address is not set by:
> 
> load mmc 0:1 0x13000000 snp.efi
> bootefi 0x13000000
> 
> Where would an fdtadress be determined without loading a dtb?

If you instead just use

bootefi 0x13000000 $fdtcontroladdr

you should be all set :)


Alex