Hi Kim,
On 29/08/18 14:49, Kim Phillips wrote:
On Wed, 29 Aug 2018 10:44:23 +0100 Robert Walker robert.walker@arm.com wrote:
This patch adds support for generating instruction samples from trace of AArch32 programs using the A32 and T32 instruction sets.
T32 has variable 2 or 4 byte instruction size, so the conversion between addresses and instruction counts requires extra information from the trace decoder, requiring version 0.9.1 of OpenCSD. A check for the new struct member has been added to the feature check for OpenCSD.
Signed-off-by: Robert Walker robert.walker@arm.com
...
+++ b/tools/build/feature/test-libopencsd.c @@ -3,6 +3,13 @@ int main(void) {
- /*
* Requires ocsd_generic_trace_elem.num_instr_range introduced in* OpenCSD 0.90.9 != 0.9.1 in the above commit text: which is it?
I'll change it to 0.9.1 if there's another version of the patch (it was introduced in 0.9, but 0.9.1 has a necessary bug fix)
*/- ocsd_generic_trace_elem elem;
- (void)elem.num_instr_range;
This breaks building against older versions of OpenCSD, right?
(void)ocsd_get_version();
Why don't we maintain building against older versions of the library, and use the version information to make the decision on whether to use the new feature being introduced in this patch?
The intention is to fail the feature detection check if the older version is installed - perf will still compile, but without the CoreSight trace support.
OpenCSD is still in development, so new features like this are being added and it would add a lot of #ifdef mess to the perf code to continue to support any machines with the old library version installed - there will only be a handful of machines affected and it's trivial to upgrade them (the new Debian packages are available). How long would we continue to support such an older version? I also don't see any precedent for supporting multiple dependent library versions in perf.
Thanks,
Kim
Regards
Rob