On 8/13/24 01:39, Ilpo Järvinen wrote:
On Mon, 12 Aug 2024, Reinette Chatre wrote:
On 8/12/24 3:49 PM, Shuah Khan wrote:
On 8/9/24 02:45, Ilpo Järvinen wrote:
Adding Maciej.
On Fri, 9 Aug 2024, Muhammad Usama Anjum wrote:
On 8/9/24 12:23 PM, Ilpo Järvinen wrote:
On Fri, 9 Aug 2024, Muhammad Usama Anjum wrote:
This test doesn't have support for other architectures. Altough
resctrl
is supported on x86 and ARM, but arch_supports_noncont_cat() shows
that
only x86 for AMD and Intel are supported by the test.
One does not follow from the other. arch_supports_noncont_cat() is
only
small part of the tests so saying "This test" based on a small subset
of
all tests is bogus. Also, I don't see any reason why ARCH_ARM could
not be
added and arch_supports_noncont_cat() adapted accordingly.
I'm not familiar with resctrl and the architectural part of it. Feel
free to fix it and ignore this patch.
If more things are missing than just adjusting
arch_supports_noncont_cat(), the test should be turned off until proper
support is added to the test.
We get build
errors when built for ARM and ARM64.
As this seems the real reason, please quote any errors when you use
them
as justification so it can be reviewed if the reasoning is sound or
not.
CC resctrl_tests
In file included from resctrl.h:24,
from cat_test.c:11:
In function 'arch_supports_noncont_cat',
inlined from 'noncont_cat_run_test' at cat_test.c:323:6:
../kselftest.h:74:9: error: impossible constraint in 'asm'
74 | __asm__ __volatile__ ("cpuid\n\t"
\
| ^~~~~~~
cat_test.c:301:17: note: in expansion of macro '__cpuid_count'
301 | __cpuid_count(0x10, 1, eax, ebx, ecx, edx);
| ^~~~~~~~~~~~~
../kselftest.h:74:9: error: impossible constraint in 'asm'
74 | __asm__ __volatile__ ("cpuid\n\t"
\
| ^~~~~~~
cat_test.c:303:17: note: in expansion of macro '__cpuid_count'
303 | __cpuid_count(0x10, 2, eax, ebx, ecx, edx);
| ^~~~~~~~~~~~~
Okay, so it's specific to lack of CPUID. This seems a kselftest common
level problem to me, since __cpuid_count() is provided in kselftest.h.
Shuah (or others), what is the intended mechanism for selftests to know if
it can be used or not since as is, it's always defined?
_cpuid_count() gets defined in ksefltest.h if it can't find it.
As the comment says both gcc and cland probide __cpuid_count()
gcc cpuid.h provides __cpuid_count() since v4.4.
Clang/LLVM cpuid.h provides __cpuid_count() since v3.4.0.
I see some Makefiles use compile testing a trivial program to decide
whether
they build some x86_64 tests or not. Is that what should be done here too,
test if __cpuid_count() compiles or not (and then build some #ifdeffery
based on the result of that compile testing)?
These build errors need to be fixed instead of restricting the build> In
some cases when the test can't be supported on an architecture then it is
okay
to suppress build. This is not a general solution to suppress build warnings
While there is an effort to support Arm in resctrl [1], this is not currently
the case and the resctrl selftests as a consequence only support x86 with
built-in assumptions that a test runs on either AMD or Intel. After the kernel
gains support
for Arm more changes will be needed for the resctrl tests to support another
architecture
so I do think the most appropriate change to address this build failure is to
restrict
resctrl tests to x86.
While ARM lacks resctrl support at the moment (the patch BTW claims
otherwise), this problem is general-level problem in selftests. When
somebody includes kselftest.h, the header provided __cpuid_count() which
seems to not be compilable on ARMs (even if the test itself would never
call it on other than when running on Intel). Some #ifdeffery is necessary
either in kselftest.h or in the test code.
I would recommend against adding suppress build code when it can be fixed.
I expect after resctrl fs obtains support for Arm the resctrl selftests can be
updated to support it with more fine grained architectural checks than a
global
enable/disable needed at this time.
That won't help to a build failure. The build would fail on ARM even if
there's some resctrl specific test for arch done by the test itself.
I see.
Let's investigate this problem to fix it properly. I don't see any arm and
arm64
maintainers and developers on this thread. It would be good to investigate
to
see if this can be fixed.
Yes, I was hoping there would be a general level solution which would
provide e.g. HAS_CPUID_COUNT or an empty stub for __cpuid_count() or
something along those lines.
Can we try to make this change?
thanks,
-- Shuah
