* powerpc build fail
@ 2017-02-21 10:53 Tobin C. Harding
2017-02-21 23:37 ` Tobin C. Harding
0 siblings, 1 reply; 2+ messages in thread
From: Tobin C. Harding @ 2017-02-21 10:53 UTC (permalink / raw)
To: kernelnewbies
The current (2bfe01e) torvalds git tree fails to build with the following error
arch/powerpc/kernel/time.c: In function ?running_clock?:
arch/powerpc/kernel/time.c:712:25: error: implicit declaration of function ?cputime_to_nsecs? [-Werror=implicit-function-declaration]
return local_clock() - cputime_to_nsecs(kcpustat_this_cpu->cpustat[CPUTIME_STEAL]);
^
I would like to do more than just file a bug report. Further
investigation (cputime.h) shows that cputime_to_nsecs has a
preprocessor guard on the config option (currently enabled)
CONFIG_VIRT_CPU_ACCOUNTING_NATIVE.
CONFIG_PPC_PSERIES is also enabled.
The offending code in arch/powerpc/kernel/time.c is
#ifdef CONFIG_PPC_PSERIES
/*
* Running clock - attempts to give a view of time passing for a virtualised
* kernels.
* Uses the VTB register if available otherwise a next best guess.
*/
unsigned long long running_clock(void)
{
/*
* Don't read the VTB as a host since KVM does not switch in host
* timebase into the VTB when it takes a guest off the CPU, reading the
* VTB would result in reading 'last switched out' guest VTB.
*
* Host kernels are often compiled with CONFIG_PPC_PSERIES checked, it
* would be unsafe to rely only on the #ifdef above.
*/
if (firmware_has_feature(FW_FEATURE_LPAR) &&
cpu_has_feature(CPU_FTR_ARCH_207S))
return mulhdu(get_vtb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
/*
* This is a next best approximation without a VTB.
* On a host which is running bare metal there should never be any stolen
* time and on a host which doesn't do any virtualisation TB *should* equal
* VTB so it makes no difference anyway.
*/
return local_clock() - cputime_to_nsecs(kcpustat_this_cpu->cpustat[CPUTIME_STEAL]);
}
#endif
Can anyone give me a hint on this one? Where to start reading?
thanks,
Tobin.
^ permalink raw reply [flat|nested] 2+ messages in thread* powerpc build fail
2017-02-21 10:53 powerpc build fail Tobin C. Harding
@ 2017-02-21 23:37 ` Tobin C. Harding
0 siblings, 0 replies; 2+ messages in thread
From: Tobin C. Harding @ 2017-02-21 23:37 UTC (permalink / raw)
To: kernelnewbies
On Tue, Feb 21, 2017 at 09:53:01PM +1100, Tobin C. Harding wrote:
> The current (2bfe01e) torvalds git tree fails to build with the following error
>
> arch/powerpc/kernel/time.c: In function ?running_clock?:
> arch/powerpc/kernel/time.c:712:25: error: implicit declaration of function ?cputime_to_nsecs? [-Werror=implicit-function-declaration]
> return local_clock() - cputime_to_nsecs(kcpustat_this_cpu->cpustat[CPUTIME_STEAL]);
> ^
> I would like to do more than just file a bug report. Further
> investigation (cputime.h) shows that cputime_to_nsecs has a
> preprocessor guard on the config option (currently enabled)
> CONFIG_VIRT_CPU_ACCOUNTING_NATIVE.
Mistake made, CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is *not* enabled.
$ cat .config | grep CONFIG_VIRT_CPU
# CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is not set
# CONFIG_VIRT_CPU_ACCOUNTING_GEN is not set
$ cat .config | grep CONFIG_PPC_PSERIES
CONFIG_PPC_PSERIES=y
>
> CONFIG_PPC_PSERIES is also enabled.
>
> The offending code in arch/powerpc/kernel/time.c is
>
> #ifdef CONFIG_PPC_PSERIES
>
> /*
> * Running clock - attempts to give a view of time passing for a virtualised
> * kernels.
> * Uses the VTB register if available otherwise a next best guess.
> */
> unsigned long long running_clock(void)
> {
> /*
> * Don't read the VTB as a host since KVM does not switch in host
> * timebase into the VTB when it takes a guest off the CPU, reading the
> * VTB would result in reading 'last switched out' guest VTB.
> *
> * Host kernels are often compiled with CONFIG_PPC_PSERIES checked, it
> * would be unsafe to rely only on the #ifdef above.
> */
> if (firmware_has_feature(FW_FEATURE_LPAR) &&
> cpu_has_feature(CPU_FTR_ARCH_207S))
> return mulhdu(get_vtb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
>
> /*
> * This is a next best approximation without a VTB.
> * On a host which is running bare metal there should never be any stolen
> * time and on a host which doesn't do any virtualisation TB *should* equal
> * VTB so it makes no difference anyway.
> */
> return local_clock() - cputime_to_nsecs(kcpustat_this_cpu->cpustat[CPUTIME_STEAL]);
> }
> #endif
>
> Can anyone give me a hint on this one? Where to start reading?
Removing the compile time guard allows the build to proceed, surely
this is not the correct solution though.
diff --git a/arch/powerpc/include/asm/cputime.h b/arch/powerpc/include/asm/cputime.h
index 99b5418..15482cb 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -16,7 +16,7 @@
#ifndef __POWERPC_CPUTIME_H
#define __POWERPC_CPUTIME_H
-#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+
#include <linux/types.h>
#include <linux/time.h>
@@ -53,5 +53,5 @@ void arch_vtime_task_switch(struct task_struct *tsk);
#endif
#endif /* __KERNEL__ */
-#endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
+
#endif /* __POWERPC_CPUTIME_H */
diff --git a/include/linux/cputime.h b/include/linux/cputime.h
index a691dc4..f730c14 100644
--- a/include/linux/cputime.h
+++ b/include/linux/cputime.h
@@ -1,13 +1,13 @@
#ifndef __LINUX_CPUTIME_H
#define __LINUX_CPUTIME_H
-#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+
#include <asm/cputime.h>
#ifndef cputime_to_nsecs
-# define cputime_to_nsecs(__ct) \
+#define cputime_to_nsecs(__ct) \
(cputime_to_usecs(__ct) * NSEC_PER_USEC)
#endif
-#endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
+
#endif /* __LINUX_CPUTIME_H */
thanks,
Tobin.
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