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Message-ID: <87v7yrynpf.fsf@nvidia.com>
Date: Thu, 19 Sep 2024 21:05:16 -0700
From: Rahul Rameshbabu <rrameshbabu@...dia.com>
To: Christophe ROULLIER <christophe.roullier@...s.st.com>
Cc: Richard Cochran <richardcochran@...il.com>, netdev@...r.kernel.org,
"David S. Miller" <davem@...emloft.net>, Jakub Kicinski
<kuba@...nel.org>, Shuah Khan <shuah@...nel.org>, Maciek Machnikowski
<maciek@...hnikowski.net>
Subject: Re: [BUG] Regression with commit: ptp: Add .getmaxphase callback to
ptp_clock_info
On Thu, 12 Sep, 2024 20:55:22 -0700 Richard Cochran <richardcochran@...il.com> wrote:
> On Thu, Sep 12, 2024 at 04:51:51PM +0200, Christophe ROULLIER wrote:
>> Hi Richard,
>>
>>
>> I put in attachment result of pahole.
>>
>> It is :
>>
>> struct ptp_clock_caps {
>> int max_adj; /* 0 4 */
>> int n_alarm; /* 4 4 */
>> int n_ext_ts; /* 8 4 */
>> int n_per_out; /* 12 4 */
>> int pps; /* 16 4 */
>> int n_pins; /* 20 4 */
>> int cross_timestamping; /* 24 4 */
>> int adjust_phase; /* 28 4 */
>> int max_phase_adj; /* 32 4 */
>> int rsv[11]; /* 36 44 */
>>
>> /* size: 80, cachelines: 2, members: 10 */
>> /* last cacheline: 16 bytes */
>> };
>
> Total size is 80 bytes.
>
> As expected.
>
> So I can't explain the error that you are seeing.
Could you share what kind of STM32 development board you are using (like
the model), the kernel config, and toolchain you are using to build the
kernel? I would be interested in trying to reproduce. Also could you run
pahole on the ptp kernel module, "/lib/modules/$(uname -r)/kernel/drivers/ptp/ptp.ko",
and check the size of struct ptp_clock_caps there? If it is compressed,
you will need to uncompress the kernel object.
I am having a hard time believing commit
c3b60ab7a4dff6e6e608e685b70ddc3d6b2aca81 is the fundamental culprit, but
more likely it exposes some other issue seen uniquely on armhf. My
theory is if you have another commit that changes struct ptp_clock_caps
and adds an additional used field in place of a rsv element, you would
experience the same issue.
I do not work on PTP professionally anymore, but I am interested in
looking into this.
--
Thanks,
Rahul Rameshbabu
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