linux-kernel - Re: [PATCH 2/6] coresight: Fix holes in struct etmv4

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Message-ID: <4d742477-f16a-4bc0-bb86-717bc0b560b0@linaro.org>
Date: Thu, 2 Oct 2025 11:11:30 +0100
From: James Clark <james.clark@...aro.org>
To: Mike Leach <mike.leach@...aro.org>
Cc: Suzuki K Poulose <suzuki.poulose@....com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Jonathan Corbet <corbet@....net>, Leo Yan <leo.yan@....com>,
 coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH 2/6] coresight: Fix holes in struct etmv4_config



On 14/08/2025 1:37 pm, Mike Leach wrote:
> Hi James
> 
> On Mon, 11 Aug 2025 at 10:32, James Clark <james.clark@...aro.org> wrote:
>>
>> Lots of u8s are mixed with u64s and u32s so repack it to save a bit
>> of space because there's one of these for each ETM.
>>
>> Signed-off-by: James Clark <james.clark@...aro.org>
>> ---
>>   drivers/hwtracing/coresight/coresight-etm4x.h | 19 ++++++++++++-------
>>   1 file changed, 12 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
>> index 746627476bd3..a355a1e9606d 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
>> @@ -832,28 +832,33 @@ struct etmv4_config {
>>          u32                             vipcssctlr;
>>          u8                              seq_idx;
>>          u8                              syncfreq;
>> +       u8                              cntr_idx;
>> +       u8                              res_idx;
>> +       u8                              ss_idx;
>> +       u8                              addr_idx;
>> +       u8                              addr_type[ETM_MAX_SINGLE_ADDR_CMP];
>> +       u8                              ctxid_idx;
>> +       u8                              vmid_idx;
>>          u32                             seq_ctrl[ETM_MAX_SEQ_STATES];
>>          u32                             seq_rst;
>>          u32                             seq_state;
>> -       u8                              cntr_idx;
>> +
>>          u32                             cntrldvr[ETMv4_MAX_CNTR];
>>          u32                             cntr_ctrl[ETMv4_MAX_CNTR];
>>          u32                             cntr_val[ETMv4_MAX_CNTR];
>> -       u8                              res_idx;
>> +
>>          u32                             res_ctrl[ETM_MAX_RES_SEL];
>> -       u8                              ss_idx;
>> +
>>          u32                             ss_ctrl[ETM_MAX_SS_CMP];
>>          u32                             ss_status[ETM_MAX_SS_CMP];
>>          u32                             ss_pe_cmp[ETM_MAX_SS_CMP];
>> -       u8                              addr_idx;
>> +
>>          u64                             addr_val[ETM_MAX_SINGLE_ADDR_CMP];
>>          u64                             addr_acc[ETM_MAX_SINGLE_ADDR_CMP];
>> -       u8                              addr_type[ETM_MAX_SINGLE_ADDR_CMP];
> 
> this is 16 x u8 - could this not just stay here?
> 
>> -       u8                              ctxid_idx;
>> +
>>          u64                             ctxid_pid[ETMv4_MAX_CTXID_CMP];
>>          u32                             ctxid_mask0;
>>          u32                             ctxid_mask1;
>> -       u8                              vmid_idx;
>>          u64                             vmid_val[ETM_MAX_VMID_CMP];
>>          u32                             vmid_mask0;
>>          u32                             vmid_mask1;
>>
>> --
>> 2.34.1
>>
> 
> These attributes have been functionally grouped for ease of
> understanding. If we move the _idx values away from what they are
> indexing, we probably need comments cross  referencing from where they
> where and where they have gone to.
> 
> Mike

I missed that because although there are newline separators there were 
no comments for headers. Dropped this commit in v3.

> 
>