Received-SPF: pass (google.com: domain of linux-kernel+bounces-139602-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
From: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
To: Samuel Holland <samuel.holland@sifive.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
  linux-arm-kernel@lists.infradead.org,  x86@kernel.org,
  linux-kernel@vger.kernel.org,  linux-arch@vger.kernel.org,
  linuxppc-dev@lists.ozlabs.org,  linux-riscv@lists.infradead.org,
  Christoph Hellwig <hch@lst.de>,  loongarch@lists.linux.dev,
  amd-gfx@lists.freedesktop.org,  Alex Deucher <alexander.deucher@amd.com>
Subject: Re: [PATCH v4 13/15] drm/amd/display: Use ARCH_HAS_KERNEL_FPU_SUPPORT
In-Reply-To: <75a37a4b-f516-40a3-b6b5-4aa1636f9b60@sifive.com> (Samuel
	Holland's message of "Wed, 10 Apr 2024 17:47:27 -0500")
References: <20240329072441.591471-1-samuel.holland@sifive.com>
	<20240329072441.591471-14-samuel.holland@sifive.com>
	<87wmp4oo3y.fsf@linaro.org>
	<75a37a4b-f516-40a3-b6b5-4aa1636f9b60@sifive.com>
User-Agent: mu4e 1.12.2; emacs 29.3
Date: Wed, 10 Apr 2024 22:02:09 -0300
Message-ID: <87wmp4ogoe.fsf@linaro.org>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain


Hello Samuel,

Thank you for the quick reply!

Samuel Holland <samuel.holland@sifive.com> writes:
> On 2024-04-10 5:21 PM, Thiago Jung Bauermann wrote:
>>
>> Unfortunately this patch causes build failures on arm with allyesconfig
>> and allmodconfig. Tested with next-20240410.

<snip>

> In both cases, the issue is that the toolchain requires runtime support to
> convert between `unsigned long long` and `double`, even when hardware FP is
> enabled. There was some past discussion about GCC inlining some of these
> conversions[1], but that did not get implemented.

Thank you for the explanation and the bugzilla reference. I added a
comment there mentioning that the problem came up again with this patch
series.

> The short-term fix would be to drop the `select ARCH_HAS_KERNEL_FPU_SUPPORT` for
> 32-bit arm until we can provide these runtime library functions.

Does this mean that patch 2 in this series:

[PATCH v4 02/15] ARM: Implement ARCH_HAS_KERNEL_FPU_SUPPORT

will be dropped?

--
Thiago