From: Ard Biesheuvel <ardb@kernel.org>
To: Samuel Holland <samuel.holland@sifive.com>,
Arnd Bergmann <arnd@arndb.de>
Cc: Thiago Jung Bauermann <thiago.bauermann@linaro.org>,
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
Date: Thu, 11 Apr 2024 09:15:43 +0200 [thread overview]
Message-ID: <CAMj1kXGW5XQxXrYaPhT6sCjH7s0EwqzNjWies3b8UWnUBW5Ngw@mail.gmail.com> (raw)
In-Reply-To: <4c8e63d6-ba33-47fe-8150-59eba8babf2d@sifive.com>
(cc Arnd)
On Thu, 11 Apr 2024 at 03:11, Samuel Holland <samuel.holland@sifive.com> wrote:
>
> Hi Thiago,
>
> On 2024-04-10 8:02 PM, Thiago Jung Bauermann wrote:
> > 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?
>
> No, because later patches in the series (3, 6) depend on the definition of
> CC_FLAGS_FPU from that patch. I will need to send a fixup patch unless I can
> find a GPL-2 compatible implementation of the runtime library functions.
>
Is there really a point to doing that? Do 32-bit ARM systems even have
enough address space to the map the BARs of the AMD GPUs that need
this support?
Given that this was not enabled before, I don't think the upshot of
this series should be that we enable support for something on 32-bit
ARM that may cause headaches down the road without any benefit.
So I'd prefer a fixup patch that opts ARM out of this over adding
support code for 64-bit conversions.
WARNING: multiple messages have this Message-ID (diff)
From: Ard Biesheuvel <ardb@kernel.org>
To: Samuel Holland <samuel.holland@sifive.com>,
Arnd Bergmann <arnd@arndb.de>
Cc: Thiago Jung Bauermann <thiago.bauermann@linaro.org>,
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
Date: Thu, 11 Apr 2024 09:15:43 +0200 [thread overview]
Message-ID: <CAMj1kXGW5XQxXrYaPhT6sCjH7s0EwqzNjWies3b8UWnUBW5Ngw@mail.gmail.com> (raw)
In-Reply-To: <4c8e63d6-ba33-47fe-8150-59eba8babf2d@sifive.com>
(cc Arnd)
On Thu, 11 Apr 2024 at 03:11, Samuel Holland <samuel.holland@sifive.com> wrote:
>
> Hi Thiago,
>
> On 2024-04-10 8:02 PM, Thiago Jung Bauermann wrote:
> > 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?
>
> No, because later patches in the series (3, 6) depend on the definition of
> CC_FLAGS_FPU from that patch. I will need to send a fixup patch unless I can
> find a GPL-2 compatible implementation of the runtime library functions.
>
Is there really a point to doing that? Do 32-bit ARM systems even have
enough address space to the map the BARs of the AMD GPUs that need
this support?
Given that this was not enabled before, I don't think the upshot of
this series should be that we enable support for something on 32-bit
ARM that may cause headaches down the road without any benefit.
So I'd prefer a fixup patch that opts ARM out of this over adding
support code for 64-bit conversions.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Ard Biesheuvel <ardb@kernel.org>
To: Samuel Holland <samuel.holland@sifive.com>,
Arnd Bergmann <arnd@arndb.de>
Cc: Thiago Jung Bauermann <thiago.bauermann@linaro.org>,
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
Date: Thu, 11 Apr 2024 09:15:43 +0200 [thread overview]
Message-ID: <CAMj1kXGW5XQxXrYaPhT6sCjH7s0EwqzNjWies3b8UWnUBW5Ngw@mail.gmail.com> (raw)
In-Reply-To: <4c8e63d6-ba33-47fe-8150-59eba8babf2d@sifive.com>
(cc Arnd)
On Thu, 11 Apr 2024 at 03:11, Samuel Holland <samuel.holland@sifive.com> wrote:
>
> Hi Thiago,
>
> On 2024-04-10 8:02 PM, Thiago Jung Bauermann wrote:
> > 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?
>
> No, because later patches in the series (3, 6) depend on the definition of
> CC_FLAGS_FPU from that patch. I will need to send a fixup patch unless I can
> find a GPL-2 compatible implementation of the runtime library functions.
>
Is there really a point to doing that? Do 32-bit ARM systems even have
enough address space to the map the BARs of the AMD GPUs that need
this support?
Given that this was not enabled before, I don't think the upshot of
this series should be that we enable support for something on 32-bit
ARM that may cause headaches down the road without any benefit.
So I'd prefer a fixup patch that opts ARM out of this over adding
support code for 64-bit conversions.
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
WARNING: multiple messages have this Message-ID (diff)
From: Ard Biesheuvel <ardb@kernel.org>
To: Samuel Holland <samuel.holland@sifive.com>,
Arnd Bergmann <arnd@arndb.de>
Cc: linux-arch@vger.kernel.org,
Thiago Jung Bauermann <thiago.bauermann@linaro.org>,
x86@kernel.org, linux-kernel@vger.kernel.org,
amd-gfx@lists.freedesktop.org, Christoph Hellwig <hch@lst.de>,
loongarch@lists.linux.dev,
Alex Deucher <alexander.deucher@amd.com>,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 13/15] drm/amd/display: Use ARCH_HAS_KERNEL_FPU_SUPPORT
Date: Thu, 11 Apr 2024 09:15:43 +0200 [thread overview]
Message-ID: <CAMj1kXGW5XQxXrYaPhT6sCjH7s0EwqzNjWies3b8UWnUBW5Ngw@mail.gmail.com> (raw)
In-Reply-To: <4c8e63d6-ba33-47fe-8150-59eba8babf2d@sifive.com>
(cc Arnd)
On Thu, 11 Apr 2024 at 03:11, Samuel Holland <samuel.holland@sifive.com> wrote:
>
> Hi Thiago,
>
> On 2024-04-10 8:02 PM, Thiago Jung Bauermann wrote:
> > 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?
>
> No, because later patches in the series (3, 6) depend on the definition of
> CC_FLAGS_FPU from that patch. I will need to send a fixup patch unless I can
> find a GPL-2 compatible implementation of the runtime library functions.
>
Is there really a point to doing that? Do 32-bit ARM systems even have
enough address space to the map the BARs of the AMD GPUs that need
this support?
Given that this was not enabled before, I don't think the upshot of
this series should be that we enable support for something on 32-bit
ARM that may cause headaches down the road without any benefit.
So I'd prefer a fixup patch that opts ARM out of this over adding
support code for 64-bit conversions.
next prev parent reply other threads:[~2024-04-11 7:15 UTC|newest]
Thread overview: 120+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-29 7:18 [PATCH v4 00/15] Unified cross-architecture kernel-mode FPU API Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` [PATCH v4 01/15] arch: Add ARCH_HAS_KERNEL_FPU_SUPPORT Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` [PATCH v4 02/15] ARM: Implement ARCH_HAS_KERNEL_FPU_SUPPORT Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` [PATCH v4 03/15] ARM: crypto: Use CC_FLAGS_FPU for NEON CFLAGS Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` [PATCH v4 04/15] arm64: Implement ARCH_HAS_KERNEL_FPU_SUPPORT Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` [PATCH v4 05/15] arm64: crypto: Use CC_FLAGS_FPU for NEON CFLAGS Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` [PATCH v4 06/15] lib/raid6: " Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` [PATCH v4 07/15] LoongArch: Implement ARCH_HAS_KERNEL_FPU_SUPPORT Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` [PATCH v4 08/15] powerpc: " Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` [PATCH v4 09/15] x86/fpu: Fix asm/fpu/types.h include guard Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 17:30 ` Dave Hansen
2024-03-29 17:30 ` Dave Hansen
2024-03-29 17:30 ` Dave Hansen
2024-03-29 17:30 ` Dave Hansen
2024-03-29 7:18 ` [PATCH v4 10/15] x86: Implement ARCH_HAS_KERNEL_FPU_SUPPORT Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 17:28 ` Dave Hansen
2024-03-29 17:28 ` Dave Hansen
2024-03-29 17:28 ` Dave Hansen
2024-03-29 17:28 ` Dave Hansen
2024-03-29 18:02 ` Samuel Holland
2024-03-29 18:02 ` Samuel Holland
2024-03-29 18:02 ` Samuel Holland
2024-03-29 18:02 ` Samuel Holland
2024-03-29 7:18 ` [PATCH v4 11/15] riscv: Add support for kernel-mode FPU Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` [PATCH v4 12/15] drm/amd/display: Only use hard-float, not altivec on powerpc Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-04-30 17:28 ` Harry Wentland
2024-04-30 17:28 ` Harry Wentland
2024-04-30 17:28 ` Harry Wentland
2024-04-30 17:28 ` Harry Wentland
2024-03-29 7:18 ` [PATCH v4 13/15] drm/amd/display: Use ARCH_HAS_KERNEL_FPU_SUPPORT Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-04-10 22:21 ` Thiago Jung Bauermann
2024-04-10 22:21 ` Thiago Jung Bauermann
2024-04-10 22:21 ` Thiago Jung Bauermann
2024-04-10 22:21 ` Thiago Jung Bauermann
2024-04-10 22:47 ` Samuel Holland
2024-04-10 22:47 ` Samuel Holland
2024-04-10 22:47 ` Samuel Holland
2024-04-10 22:47 ` Samuel Holland
2024-04-11 1:02 ` Thiago Jung Bauermann
2024-04-11 1:02 ` Thiago Jung Bauermann
2024-04-11 1:02 ` Thiago Jung Bauermann
2024-04-11 1:02 ` Thiago Jung Bauermann
2024-04-11 1:11 ` Samuel Holland
2024-04-11 1:11 ` Samuel Holland
2024-04-11 1:11 ` Samuel Holland
2024-04-11 1:11 ` Samuel Holland
2024-04-11 1:27 ` Thiago Jung Bauermann
2024-04-11 1:27 ` Thiago Jung Bauermann
2024-04-11 1:27 ` Thiago Jung Bauermann
2024-04-11 1:27 ` Thiago Jung Bauermann
2024-04-11 7:15 ` Ard Biesheuvel [this message]
2024-04-11 7:15 ` Ard Biesheuvel
2024-04-11 7:15 ` Ard Biesheuvel
2024-04-11 7:15 ` Ard Biesheuvel
2024-04-11 7:31 ` Arnd Bergmann
2024-04-11 7:31 ` Arnd Bergmann
2024-04-11 7:31 ` Arnd Bergmann
2024-04-11 7:31 ` Arnd Bergmann
2024-04-12 1:54 ` Dave Airlie
2024-04-12 1:54 ` Dave Airlie
2024-04-12 1:54 ` Dave Airlie
2024-04-12 1:54 ` Dave Airlie
2024-04-30 17:29 ` Harry Wentland
2024-04-30 17:29 ` Harry Wentland
2024-04-30 17:29 ` Harry Wentland
2024-04-30 17:29 ` Harry Wentland
2024-03-29 7:18 ` [PATCH v4 14/15] selftests/fpu: Move FP code to a separate translation unit Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` [PATCH v4 15/15] selftests/fpu: Allow building on other architectures Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-03-29 7:18 ` Samuel Holland
2024-04-03 12:51 ` [PATCH v4 00/15] Unified cross-architecture kernel-mode FPU API Christian König
2024-04-03 12:51 ` Christian König
2024-04-03 12:51 ` Christian König
2024-04-03 12:51 ` Christian König
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