Quoting Guenter Roeck (2024-09-28 14:32:35)
On 9/28/24 12:27, Shuah Khan wrote:
On 9/28/24 11:54, Shuah Khan wrote:
On 9/28/24 11:31, Guenter Roeck wrote:
On 9/27/24 17:08, Guenter Roeck wrote:
On 9/27/24 13:45, Shuah Khan wrote:
On 9/27/24 10:19, Guenter Roeck wrote: > Copying devicetree maintainers. > > On Thu, Sep 26, 2024 at 09:39:38PM -0700, Guenter Roeck wrote: >> On Thu, Sep 26, 2024 at 09:14:11PM -0700, Guenter Roeck wrote: >>> Hi Stephen, >>> >>> On Thu, Jul 18, 2024 at 02:05:07PM -0700, Stephen Boyd wrote: >>>> Test that clks registered with 'struct clk_parent_data' work as >>>> intended and can find their parents. >>>> >>> >>> When testing this on arm64, I see the error below. The error is only >>> seen if I boot through efi, i.e., with "-bios QEMU_EFI-aarch64.fd" >>> qemu parameter. >>> >>> Any idea what might cause the problem ? >>> >> I noticed that the new overlay tests fail as well, also with "path '/' not >> found". >> >> [Maybe] answering my own question: I think the problem may be that there >> is no devicetree file and thus no devicetree root when booting through >> efi (in other words, of_root is NULL). Would it make sense to skip the >> tests in that case ? >> > > The problem is that of_root is not initialized in arm64 boots if ACPI > is enabled. > > From arch/arm64/kernel/setup.c:setup_arch(): > > if (acpi_disabled) > unflatten_device_tree(); // initializes of_root
Oof I forgot that Rob didn't apply the patch that let an empty root live on ARM64 ACPI systems. See this thread[1] for all the details.
> > ACPI is enabled if the system boots from EFI. This also affects > CONFIG_OF_KUNIT_TEST, which explicitly checks if of_root exists and > fails the test if it doesn't. > > I think those tests need to add a check for this condition, or affected > machines won't be able to run those unit tests. The obvious solution would > be to check if of_root is set, but then the associated test case in > CONFIG_OF_KUNIT_TEST would not make sense. > > Any suggestions ? >
I think that's the best we can do for now. Basically add a check like
if (IS_ENABLED(CONFIG_ARM64) && acpi_disabled) kunit_skip(test, "ARM64 + ACPI rejects DT overlays");
to the overlay application function and the DT test.
Would it work if these tests check if acpi_disabled and skip if it isn't disabled? It might be low overhead condition to check from these tests.
acpi_disabled is exported:
arch/arm64/kernel/acpi.c:EXPORT_SYMBOL(acpi_disabled); arch/loongarch/kernel/acpi.c:EXPORT_SYMBOL(acpi_disabled); arch/riscv/kernel/acpi.c:EXPORT_SYMBOL(acpi_disabled); arch/x86/kernel/acpi/boot.c:EXPORT_SYMBOL(acpi_disabled);
I don't think that would work. Looking through the use of acpi_init, I don't think that of_root is always NULL when acpi_init is false; that just happens to be the case on arm64 when booting through efi. However, even arm64 has the following code.
if (acpi_disabled) psci_dt_init(); else psci_acpi_init();
While psci_dt_init() doesn't set of_root, it does try to do a devicetree match. So there must be some other condition where acpi_disabled is set but of_root is set anyway. I just have not found that code path.
I ended up disabling all affected unit tests for arm64. I'll do the same for other architectures if I encounter the problem there as well.
Unfortunately that includes all clock unit tests because the tests requiring devicetree support can not be enabled/disabled separately, but that can't be helped and is still better than "mandatory" failures.
of_root is set in drivers/of/pdt.c when it creates the root node. This could be a definitive test for kunit tests that depend on devicetree support.
That is not always the case, including arm64. It is primarily set in unflatten_devicetree(), which is not called on arm64 unless acpi_is disabled (see above).
It is an exported symbol. drivers/of/base.c exports it.
Yes, checking if of_root is NULL and skipping the test in that case might help, but then there is the of_dtb_root_node_populates_of_root unit test which explicitly fails if of_root is NULL. The comment describing the test is
/*
- Test that the 'of_root' global variable is always populated when DT code is
- enabled. Remove this test once of_root is removed from global access.
*/
The devicetree unit test code explicitly assumes that of_root is set if CONFIG_OF_EARLY_FLATTREE is enabled, but that is not always the case (again, of_root is NULL on arm64 unless acpi is disabled).
That DT test has been there for a few releases. Is this the first time those tests have been run on arm64+acpi? I didn't try after sending the patches and forgot that the patch was dropped.
How are you running kunit tests? I installed the qemu-efi-aarch64 debian package to get QEMU_EFI.fd but passing that to the kunit.py run command with --qemu_args="-bios /usr/share/qemu-efi-aarch64/QEMU_EFI.fd" didn't get me beyond the point that the EFI stub boots linux. I think the serial console must not be working and thus the kunit wrapper waits for something to show up but nothing ever does. I haven't dug any further though, so maybe you have a working command.
Here's my command that isn't working:
./tools/testing/kunit/kunit.py run --arch=arm64 --kunitconfig=drivers/of --qemu_args="-bios /usr/share/qemu-efi-aarch64/QEMU_EFI.fd"
[1] https://lore.kernel.org/all/20240217010557.2381548-6-sboyd@kernel.org/