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
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 ?
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.
I am hoping Stephen will have a solution for this problem. In the meantime,
I will look into this to see if we can find a check that works.
thanks,
-- Shuah
