Hi James,

On Thu, Apr 15, 2021 at 05:13:36PM +0300, James Clark wrote:

On 12/04/2021 12:10, Leo Yan wrote:

quoted

The enum value 'ARM_SPE_PER_CPU_MMAPS' is never used so remove it.

Hi Leo,

I think this causes an error when attempting to open a newly recorded file
with an old version of perf. The value ARM_SPE_AUXTRACE_PRIV_MAX is used here:

	size_t min_sz = sizeof(u64) * ARM_SPE_AUXTRACE_PRIV_MAX;
	struct perf_record_time_conv *tc = &session->time_conv;
	struct arm_spe *spe;
	int err;

	if (auxtrace_info->header.size < sizeof(struct perf_record_auxtrace_info) +
					min_sz)
		return -EINVAL;

And removing ARM_SPE_PER_CPU_MMAPS changes the value of ARM_SPE_AUXTRACE_PRIV_MAX.

At least I think that's what's causing the problem. I get this error:

	./perf report -i per-thread-spe-time.data
	0x1c0 [0x18]: failed to process type: 70 [Invalid argument]
	Error:
	failed to process sample
	# To display the perf.data header info, please use --header/--header-only options.
	#

Yes, when working on this patch I had concern as well.

I carefully thought that the perf tool should be backwards-compatible,
but there have no requirement for forwards-compatibility.  This is the
main reason why I kept this patch.

If you or anyone could confirm the forwards-compatibility is required,
it's quite fine for me to drop this patch.

Thanks a lot for the reviewing and testing!
Leo

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