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path: root/tools/lib/str_error_r.c
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#undef _GNU_SOURCE
#include <string.h>
#include <stdio.h>
#include <linux/string.h>

/*
 * The tools so far have been using the strerror_r() GNU variant, that returns
 * a string, be it the buffer passed or something else.
 *
 * But that, besides being tricky in cases where we expect that the function
 * using strerror_r() returns the error formatted in a provided buffer (we have
 * to check if it returned something else and copy that instead), breaks the
 * build on systems not using glibc, like Alpine Linux, where musl libc is
 * used.
 *
 * So, introduce yet another wrapper, str_error_r(), that has the GNU
 * interface, but uses the portable XSI variant of strerror_r(), so that users
 * rest asured that the provided buffer is used and it is what is returned.
 */
char *str_error_r(int errnum, char *buf, size_t buflen)
{
	int err = strerror_r(errnum, buf, buflen);
	if (err)
		snprintf(buf, buflen, "INTERNAL ERROR: strerror_r(%d, %p, %zd)=%d", errnum, buf, buflen, err);
	return buf;
}
colspan='2' class='oid'>3c223c19aea85d3dda1416c187915f4a30b04b1f (diff)
cpufreq: intel_pstate: Disable energy efficiency optimization
Some Kabylake desktop processors may not reach max turbo when running in HWP mode, even if running under sustained 100% utilization. This occurs when the HWP.EPP (Energy Performance Preference) is set to "balance_power" (0x80) -- the default on most systems. It occurs because the platform BIOS may erroneously enable an energy-efficiency setting -- MSR_IA32_POWER_CTL BIT-EE, which is not recommended to be enabled on this SKU. On the failing systems, this BIOS issue was not discovered when the desktop motherboard was tested with Windows, because the BIOS also neglects to provide the ACPI/CPPC table, that Windows requires to enable HWP, and so Windows runs in legacy P-state mode, where this setting has no effect. Linux' intel_pstate driver does not require ACPI/CPPC to enable HWP, and so it runs in HWP mode, exposing this incorrect BIOS configuration. There are several ways to address this problem. First, Linux can also run in legacy P-state mode on this system. As intel_pstate is how Linux enables HWP, booting with "intel_pstate=disable" will run in acpi-cpufreq/ondemand legacy p-state mode. Or second, the "performance" governor can be used with intel_pstate, which will modify HWP.EPP to 0. Or third, starting in 4.10, the /sys/devices/system/cpu/cpufreq/policy*/energy_performance_preference attribute in can be updated from "balance_power" to "performance". Or fourth, apply this patch, which fixes the erroneous setting of MSR_IA32_POWER_CTL BIT_EE on this model, allowing the default configuration to function as designed. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Reviewed-by: Len Brown <len.brown@intel.com> Cc: 4.6+ <stable@vger.kernel.org> # 4.6+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'net/rose/rose_subr.c')