Re: [LTP] high_freq_hwp_cap_cppc.c: new test

[linuxtestproject.agent@gmail.com]

Hi Piotr,

On Tue, Jun 9 2026, Piotr Kubaj wrote:
> high_freq_hwp_cap_cppc.c: new test

> +#include "tst_test.h"
> +#include "tst_safe_prw.h"
> +#include "lapi/cpuid.h"

lapi/cpuid.h contains #error on non-x86 architectures and
__cpuid_count uses x86 inline assembly, so this file will not
compile on ARM, s390x, etc.

Ground rule 6 requires architecture-specific tests to still compile
everywhere. The existing ptrace07.c shows the correct pattern:
wrap the entire file body in
#if defined(__i386__) || defined(__x86_64__) with a
TST_TEST_TCONF("test requires x86") in the #else branch.

> +	for (int i = 0; i < nproc; i++)
> +		tst_res(TINFO, "cpu%d: %s", i, mismatch[i] ? "MISMATCH" : "OK");

Offline CPUs are skipped during the comparison loop but the
summary still prints "OK" for them (mismatch[i] is zero from
memset). This is misleading -- "OK" implies the values matched
when no check was performed. Consider skipping offline CPUs here
too, or printing "OFFLINE" instead.

> +/*\
> + * Verify for all online logical CPUs that their highest performance value are
> + * the same for HWP Capability MSR 0x771 and CPPC sysfs file.

The test sets .needs_root = 1 but the doc comment does not explain
why root is required. Per the LTP guidelines, the reason should be
stated (reading /dev/cpu/N/msr needs CAP_SYS_RAWIO / root).

Verdict: Needs revision

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