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[PATCH] arch: um/x86: Select ARCH_SUPPORTS_ATOMIC_RMW for UML_X86

Boqun Feng posted 1 patch 1 month ago 
arch/x86/um/Kconfig | 1 +
1 file changed, 1 insertion(+)
[PATCH] arch: um/x86: Select ARCH_SUPPORTS_ATOMIC_RMW for UML_X86
Posted by Boqun Feng 1 month ago 
x86 atomic instructions are used for um on UML_X86, therefore atomics
on UML_X86 support native atomic RmW as x86 does, hence select
ARCH_SUPPORTS_ATOMIC_RMW.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
UM & x86 maintainers,

I need this to avoid a build error for Rust atomics since Rust currently
only support Atomic<i8/i16> on ARCH_SUPPORTS_ATOMIC_RMW archs. I will
add it to my upcoming PR if I get some Acked-by, thanks!

 arch/x86/um/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig
index bdd7c8e39b01..44b12e45f9a0 100644
--- a/arch/x86/um/Kconfig
+++ b/arch/x86/um/Kconfig
@@ -9,6 +9,7 @@ endmenu
 config UML_X86
 	def_bool y
 	select ARCH_USE_QUEUED_RWLOCKS
+	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_USE_QUEUED_SPINLOCKS
 	select DCACHE_WORD_ACCESS
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
-- 
2.51.0
Re: [PATCH] arch: um/x86: Select ARCH_SUPPORTS_ATOMIC_RMW for UML_X86
Posted by Richard Weinberger 1 month ago 
----- Ursprüngliche Mail -----
> Von: "Boqun Feng" <boqun.feng@gmail.com>
> An: "linux-um" <linux-um@lists.infradead.org>, "x86" <x86@kernel.org>
> CC: "richard" <richard@nod.at>, "anton ivanov" <anton.ivanov@cambridgegreys.com>, "Johannes Berg"
> <johannes@sipsolutions.net>, "tglx" <tglx@linutronix.de>, "mingo" <mingo@redhat.com>, "bp" <bp@alien8.de>, "dave
> hansen" <dave.hansen@linux.intel.com>, "hpa" <hpa@zytor.com>, "Miguel Ojeda" <ojeda@kernel.org>, "Boqun Feng"
> <boqun.feng@gmail.com>, "Gary Guo" <gary@garyguo.net>, "Björn Roy Baron" <bjorn3_gh@protonmail.com>, "Benno Lossin"
> <lossin@kernel.org>, "Andreas Hindborg" <a.hindborg@kernel.org>, "Alice Ryhl" <aliceryhl@google.com>, "Trevor Gross"
> <tmgross@umich.edu>, "dakr" <dakr@kernel.org>, "linux-kernel" <linux-kernel@vger.kernel.org>, "Rust for Linux Kernel"
> <rust-for-linux@vger.kernel.org>, "FUJITA Tomonori" <fujita.tomonori@gmail.com>
> Gesendet: Dienstag, 6. Januar 2026 04:40:34
> Betreff: [PATCH] arch: um/x86: Select ARCH_SUPPORTS_ATOMIC_RMW for UML_X86

> x86 atomic instructions are used for um on UML_X86, therefore atomics
> on UML_X86 support native atomic RmW as x86 does, hence select
> ARCH_SUPPORTS_ATOMIC_RMW.
> 
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> ---
> UM & x86 maintainers,
> 
> I need this to avoid a build error for Rust atomics since Rust currently
> only support Atomic<i8/i16> on ARCH_SUPPORTS_ATOMIC_RMW archs. I will
> add it to my upcoming PR if I get some Acked-by, thanks!
> 
> arch/x86/um/Kconfig | 1 +
> 1 file changed, 1 insertion(+)

Acked-by: Richard Weinberger <richard@nod.at>

Thanks,
//richard
Re: [PATCH] arch: um/x86: Select ARCH_SUPPORTS_ATOMIC_RMW for UML_X86
Posted by Boqun Feng 1 month ago 
On Tue, Jan 06, 2026 at 03:20:43PM +0100, Richard Weinberger wrote:
> ----- Ursprüngliche Mail -----
> > Von: "Boqun Feng" <boqun.feng@gmail.com>
> > An: "linux-um" <linux-um@lists.infradead.org>, "x86" <x86@kernel.org>
> > CC: "richard" <richard@nod.at>, "anton ivanov" <anton.ivanov@cambridgegreys.com>, "Johannes Berg"
> > <johannes@sipsolutions.net>, "tglx" <tglx@linutronix.de>, "mingo" <mingo@redhat.com>, "bp" <bp@alien8.de>, "dave
> > hansen" <dave.hansen@linux.intel.com>, "hpa" <hpa@zytor.com>, "Miguel Ojeda" <ojeda@kernel.org>, "Boqun Feng"
> > <boqun.feng@gmail.com>, "Gary Guo" <gary@garyguo.net>, "Björn Roy Baron" <bjorn3_gh@protonmail.com>, "Benno Lossin"
> > <lossin@kernel.org>, "Andreas Hindborg" <a.hindborg@kernel.org>, "Alice Ryhl" <aliceryhl@google.com>, "Trevor Gross"
> > <tmgross@umich.edu>, "dakr" <dakr@kernel.org>, "linux-kernel" <linux-kernel@vger.kernel.org>, "Rust for Linux Kernel"
> > <rust-for-linux@vger.kernel.org>, "FUJITA Tomonori" <fujita.tomonori@gmail.com>
> > Gesendet: Dienstag, 6. Januar 2026 04:40:34
> > Betreff: [PATCH] arch: um/x86: Select ARCH_SUPPORTS_ATOMIC_RMW for UML_X86
> 
> > x86 atomic instructions are used for um on UML_X86, therefore atomics
> > on UML_X86 support native atomic RmW as x86 does, hence select
> > ARCH_SUPPORTS_ATOMIC_RMW.
> > 
> > Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> > ---
> > UM & x86 maintainers,
> > 
> > I need this to avoid a build error for Rust atomics since Rust currently
> > only support Atomic<i8/i16> on ARCH_SUPPORTS_ATOMIC_RMW archs. I will
> > add it to my upcoming PR if I get some Acked-by, thanks!
> > 
> > arch/x86/um/Kconfig | 1 +
> > 1 file changed, 1 insertion(+)
> 
> Acked-by: Richard Weinberger <richard@nod.at>
> 

Queued with both tags applied, thank you both!

Regards,
Boqun

> Thanks,
> //richard
Re: [PATCH] arch: um/x86: Select ARCH_SUPPORTS_ATOMIC_RMW for UML_X86
Posted by FUJITA Tomonori 1 month ago 
On Tue,  6 Jan 2026 11:40:34 +0800
Boqun Feng <boqun.feng@gmail.com> wrote:

> x86 atomic instructions are used for um on UML_X86, therefore atomics
> on UML_X86 support native atomic RmW as x86 does, hence select
> ARCH_SUPPORTS_ATOMIC_RMW.
> 
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>

Reviewed-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
[tip: locking/core] arch: um/x86: Select ARCH_SUPPORTS_ATOMIC_RMW for UML_X86
Posted by tip-bot2 for Boqun Feng 3 weeks, 4 days ago 
The following commit has been merged into the locking/core branch of tip:

Commit-ID:     cf4c3bc1445152c1949a4b5fef56d07579fadb1e
Gitweb:        https://git.kernel.org/tip/cf4c3bc1445152c1949a4b5fef56d07579fadb1e
Author:        Boqun Feng <boqun.feng@gmail.com>
AuthorDate:    Tue, 06 Jan 2026 11:40:34 +08:00
Committer:     Boqun Feng <boqun.feng@gmail.com>
CommitterDate: Fri, 09 Jan 2026 19:01:41 +08:00

arch: um/x86: Select ARCH_SUPPORTS_ATOMIC_RMW for UML_X86

x86 atomic instructions are used for um on UML_X86, therefore atomics
on UML_X86 support native atomic RmW as x86 does, hence select
ARCH_SUPPORTS_ATOMIC_RMW.

Reviewed-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Acked-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20260106034034.60074-1-boqun.feng@gmail.com
---
 arch/x86/um/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig
index bdd7c8e..44b12e4 100644
--- a/arch/x86/um/Kconfig
+++ b/arch/x86/um/Kconfig
@@ -9,6 +9,7 @@ endmenu
 config UML_X86
 	def_bool y
 	select ARCH_USE_QUEUED_RWLOCKS
+	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_USE_QUEUED_SPINLOCKS
 	select DCACHE_WORD_ACCESS
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS

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