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From: Rob Herring <robh@kernel.org>
To: Nathan Chancellor <nathan@kernel.org>
Cc: srinivas.neeli@amd.com, wim@linux-watchdog.org,
	shubhrajyoti.datta@amd.com, michal.simek@amd.com,
	linux@roeck-us.net, ndesaulniers@google.com, trix@redhat.com,
	linux-watchdog@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, patches@lists.linux.dev,
	llvm@lists.linux.dev
Subject: Re: [PATCH] watchdog: xilinx_wwdt: Use div_u64() in xilinx_wwdt_start()
Date: Wed, 23 Aug 2023 10:18:51 -0500	[thread overview]
Message-ID: <20230823151851.GA2359738-robh@kernel.org> (raw)
In-Reply-To: <20230815-watchdog-xilinx-div_u64-v1-1-20b0b5a65c2e@kernel.org>

On Tue, Aug 15, 2023 at 12:06:50PM -0700, Nathan Chancellor wrote:
> After commit f1a43aadb5a6 ("watchdog: Enable COMPILE_TEST for more
> drivers"), it is possible to enable this driver on 32-bit architectures.
> When building for those architectures with clang, there is an error due
> to a 64-bit division in xilinx_wwdt_start():
> 
>   ERROR: modpost: "__aeabi_uldivmod" [drivers/watchdog/xilinx_wwdt.ko] undefined!
> 
> Use div_u64() to fix this, which takes a 64-bit dividend and 32-bit
> divisor. GCC likely avoids the same error due to optimizations it
> employs to transform division by a constant into other equivalent
> operations, which may be different than what is implemented in clang.
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/1915
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
>  drivers/watchdog/xilinx_wwdt.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Thanks for the fix. Also reported by 0-day with a similar failure:

All errors (new ones prefixed by >>):

   microblaze-linux-ld: drivers/watchdog/xilinx_wwdt.o: in function `xilinx_wwdt_start':
>> drivers/watchdog/xilinx_wwdt.c:74: undefined reference to `__udivdi3'


Acked-by: Rob Herring <robh@kernel.org>

WARNING: multiple messages have this Message-ID (diff)
From: Rob Herring <robh@kernel.org>
To: Nathan Chancellor <nathan@kernel.org>
Cc: srinivas.neeli@amd.com, wim@linux-watchdog.org,
	shubhrajyoti.datta@amd.com, michal.simek@amd.com,
	linux@roeck-us.net, ndesaulniers@google.com, trix@redhat.com,
	linux-watchdog@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, patches@lists.linux.dev,
	llvm@lists.linux.dev
Subject: Re: [PATCH] watchdog: xilinx_wwdt: Use div_u64() in xilinx_wwdt_start()
Date: Wed, 23 Aug 2023 10:18:51 -0500	[thread overview]
Message-ID: <20230823151851.GA2359738-robh@kernel.org> (raw)
In-Reply-To: <20230815-watchdog-xilinx-div_u64-v1-1-20b0b5a65c2e@kernel.org>

On Tue, Aug 15, 2023 at 12:06:50PM -0700, Nathan Chancellor wrote:
> After commit f1a43aadb5a6 ("watchdog: Enable COMPILE_TEST for more
> drivers"), it is possible to enable this driver on 32-bit architectures.
> When building for those architectures with clang, there is an error due
> to a 64-bit division in xilinx_wwdt_start():
> 
>   ERROR: modpost: "__aeabi_uldivmod" [drivers/watchdog/xilinx_wwdt.ko] undefined!
> 
> Use div_u64() to fix this, which takes a 64-bit dividend and 32-bit
> divisor. GCC likely avoids the same error due to optimizations it
> employs to transform division by a constant into other equivalent
> operations, which may be different than what is implemented in clang.
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/1915
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
>  drivers/watchdog/xilinx_wwdt.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Thanks for the fix. Also reported by 0-day with a similar failure:

All errors (new ones prefixed by >>):

   microblaze-linux-ld: drivers/watchdog/xilinx_wwdt.o: in function `xilinx_wwdt_start':
>> drivers/watchdog/xilinx_wwdt.c:74: undefined reference to `__udivdi3'


Acked-by: Rob Herring <robh@kernel.org>

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  parent reply	other threads:[~2023-08-23 15:18 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-15 19:06 [PATCH] watchdog: xilinx_wwdt: Use div_u64() in xilinx_wwdt_start() Nathan Chancellor
2023-08-15 19:06 ` Nathan Chancellor
2023-08-15 20:07 ` Guenter Roeck
2023-08-15 20:07   ` Guenter Roeck
2023-08-23 15:18 ` Rob Herring [this message]
2023-08-23 15:18   ` Rob Herring

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