Public bug reported:
[Impact]
AMD Embedded+ platforms need Device Tree support on x86 to describe
IP blocks implemented in PCIe-attached FPGAs. Loading an overlay for
a particular FPGA design allows existing Device Tree-based drivers
to be reused without porting each driver to ACPI.
The required configuration options are currently disabled or absent
from the amd64 configuration.
[Fix]
Enable the following options for amd64 in linux-amd-embedded:
CONFIG_OF=y
Enable the core Device Tree infrastructure used to represent device
nodes and properties in the kernel.
CONFIG_OF_OVERLAY=y
Enable support for applying Device Tree overlays at runtime.
This also selects the dynamic tree, flattened tree and phandle
resolution support required by overlays.
CONFIG_DTC=y
Enable the Device Tree compiler used during the kernel build to
compile Device Tree sources into flattened binary form. This option
is also selected through CONFIG_OF_FLATTREE.
CONFIG_PCI_DYNAMIC_OF_NODES=y
Enable creation of Device Tree nodes for PCI devices, providing
nodes to which an FPGA driver can attach an overlay describing
downstream devices. This requires CONFIG_OF_IRQ and selects
CONFIG_OF_DYNAMIC.
Synchronize the dependent amd64 configuration entries exposed by
enabling CONFIG_OF. Most newly visible optional drivers remain
explicitly disabled.
Keep all overrides in the linux-amd-embedded configuration.
The arm64 configuration and shared generic configuration remain
unchanged. This change does not add an FPGA Discovery driver.
[Test Plan]
Export the amd64 configuration and run olddefconfig.
Verify that all four requested options remain set to y.
Run the Ubuntu annotations check against the resulting configuration.
Compare the arm64 configuration before and after the change.
These configuration checks pass. The arm64 export is identical.
Full kernel build and runtime overlay testing remain to be done.
[Where problems could occur]
Enabling CONFIG_OF exposes additional configuration symbols and
automatically selects supporting infrastructure. Incorrect or
incomplete annotations could cause configuration checks to fail
or produce unintended amd64 configuration changes.
** Affects: linux (Ubuntu)
Importance: High
Assignee: Krystian Kaniewski (kkaniewski)
Status: Confirmed
** Changed in: linux (Ubuntu)
Assignee: (unassigned) => Krystian Kaniewski (kkaniewski)
** Changed in: linux (Ubuntu)
Importance: Undecided => High
** Changed in: linux (Ubuntu)
Status: New => Confirmed
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https://bugs.launchpad.net/bugs/2167567
Title:
[Resolute] Enable Device Tree overlays on amd64 for PCIe-attached
FPGAs
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