Hi Paul,
Paul Goyette wrote:
> I have managed to provide access to all of the kernel history data via
> sysctl, and I've come up with a modified version of vmstat(1) that can
> read the data from sysctl rather than having to use kvm.
Great to see more progress on sysctls instead of kvm(3)!
> Diffs for sys/sys/kernhist.h and sys/kern/kern_history.c can be found at
> www.netbsd.org/~pgoyette/my_vmstat/kernhist.diffs In the same directory
> you can find a source file my_vmstat.c (and its associated Makefile).
>
> Please review and comment (preferably constructively), and let me know
> what more needs to be done before it gets committed.
One thing to be careful of is 64-bit safe alignment of the sysctl
structures. The first structure is ok:
+/* info for a single kernhist */
+struct sysctl_history_list_entry {
+ uint32_t shle_nameoffset;
+ uint32_t shle_numentries;
+ uint32_t shle_nextfree;
+ uint32_t shle_filler;
+};
But for the second structure, I don't think the "struct timeval" is
64-bit alignment safe (unless something has changed in the last few
years):
+/* info for a single history event */
+struct sysctl_history_event {
+ struct timeval she_tv;
+ uint64_t she_callnumber;
+ uint64_t she_values[4];
+ uint32_t she_cpunum;
+ uint32_t she_fmtoffset;
+ uint32_t she_funcoffset;
+ uint32_t she_filler;
+};
Some of the original sysctl stuff used uint32_t for the seconds part of
a timeval, but I suspect you'd want to use a uint64_t nowadays. You
might end up with something like:
struct sysctl_history_event {
uint64_t she_tv_sec;
uint32_t she_tv_usec;
uint32_t she_pad1;
uint64_t she_callnumber;
uint64_t she_values[4];
...
Cheers,
Simon.
