linux-kernel - Re: [PATCH v4 2/4] watchdog: s3c2410_wdt: Fix max

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Message-ID: <30e377c4-15a2-4201-98b0-f00670af1ee2@roeck-us.net>
Date: Tue, 5 Aug 2025 06:30:30 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: sw617.shin@...sung.com, 'Sam Protsenko' <semen.protsenko@...aro.org>
Cc: krzk@...nel.org, alim.akhtar@...sung.com, wim@...ux-watchdog.org,
 khwan.seo@...sung.com, dongil01.park@...sung.com,
 linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org,
 linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/4] watchdog: s3c2410_wdt: Fix max_timeout being
 calculated larger

On 8/5/25 00:26, sw617.shin@...sung.com wrote:
> On Tuesday, August 5, 2025 at 2:03 PM Sam Protsenko <semen.protsenko@...aro.org> wrote:
> 
>>
>>>> +       u64 t_max = n_max / freq;
>>>>
>>>
>>> Make sure this compiles on 32-bit builds.
>>>
>>
>> Can you please elaborate what might be the possible problem -- just
>> curious? I admit I never though about 32-bit case when writing that code,
>> but don't see any immediate issues with that too.
>>
> 
> In my opinion, it seems that Gunter Reck's explanation is correct.
> I've found out that the error of "undefined reference to '__aeabi_uldivmod'" may occur when compiling new code on a 32-bit architecture.

Also see include/linux/math64.h. The functions implemented or declared
in that include file do have a reason to exist.

Guenter