On 5/6/20 5:01 PM, Grant Likely wrote:
On 06/05/2020 15:56, Ard Biesheuvel wrote:
On 5/6/20 4:54 PM, Grant Likely wrote:
On 06/05/2020 15:52, Ard Biesheuvel wrote:
On 5/6/20 4:38 PM, Grant Likely wrote:
Only if the door is wide open. If there is a /real need/ for a
limited set of changes to the dtb, then those specific cases can be
spelled out as things firmware is allowed to modify in a
replacement DTB. Any scenarios here need to be very specific.
What specific cases do we know about?
None. There is no way the firmware can currently manipulate the DTB
after the EFI stub has taken ownership of it. We load the firmware
provided one, copy it into a new allocation and make our changes
there. This version is the one that is passed to the OS.
Before ExitBootServices()?
Yes.
Right, so the kernel stub is completely out and language is needed for
when the DTB becomes 'sedimented'.
- Before ExitBootServices()
- After ???
No changes should be made to the DTB after it has been installed as a
config table.
Second, if an Efi application replaces the DTB, what are the known
scenarios for wanting firmware to apply fixups to the DTB (again; need
to be very specific)
None. The firmware should not expect to be given the opportunity to
tweak the DTB after it hands off to the next stage.
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