Re: [PATCH v2 15/18] perf test cs-etm: Make disassembly test use kcore

[James Clark <james.clark@linaro.org>]

On 03/06/2026 6:32 pm, Leo Yan wrote:
> On Tue, Jun 02, 2026 at 03:26:57PM +0100, James Clark wrote:
>> Hits in modules return empty disassembly with vmlinux as an input to
>> objdump. Make the disassembly test more reliable by always using kcore.
>> And update the comments to say that this is supported by the script.
> 
> Even without kcore, .ko files should have been saved into buildid
> folder. Before switch to kcore, can we firstly fix the issue that why
> .ko does not work?
> 
> Thanks,
> Leo

I think this description of the problem was wrong, the reason for 
failures was the alternatives patching mechanism. And the only way to 
fix that is by using kcore. I'm not sure what you were thinking of as a fix?

Sashiko commented on V3 that hits in modules would still open the .ko 
file and skip kcore anyway. I tried to investigate but I wasn't able to 
generate any trace or samples with hits in modules. It might be a 
regression but it might have always been like that. I do remember 
switching to static when I was tracing Coresight modules before, but 
that was to make using address filtering easier, and I inadvertently 
avoided this issue.

Seems like fixing this is outside of the scope of this test though. I 
didn't see a single failure on N1SDP and the only failures on Orion O6 
are because of the wrapping/snapshot bug, and we already knew that you 
have to use kcore to get accurate decode. So I'm not sure of a reason to 
not do it?