From: Hajime Tazaki <thehajime@gmail.com>
To: linux-um@lists.infradead.org
Cc: thehajime@gmail.com, ricarkol@google.com,
Liam.Howlett@oracle.com, linux-kernel@vger.kernel.org
Subject: [PATCH v13 11/13] um: nommu: disable SMP on nommu UML
Date: Sat, 8 Nov 2025 17:05:46 +0900 [thread overview]
Message-ID: <a9d5519fe7696def8c00a1bba7b3c6c832d5dfba.1762588860.git.thehajime@gmail.com> (raw)
In-Reply-To: <cover.1762588860.git.thehajime@gmail.com>
CONFIG_SMP doesn't work with nommu UML since fs register handling of
host does conflict with thread local storage (more specifically,
the variable signals_enabled).
Thus this commit disables the CONFIG option and the TLS variables.
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
---
arch/um/os-Linux/internal.h | 8 ++++++++
arch/x86/um/Kconfig | 2 +-
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/arch/um/os-Linux/internal.h b/arch/um/os-Linux/internal.h
index bac9fcc8c14c..25cb5cc931c1 100644
--- a/arch/um/os-Linux/internal.h
+++ b/arch/um/os-Linux/internal.h
@@ -6,6 +6,14 @@
#include <stub-data.h>
#include <signal.h>
+/* NOMMU doesn't work with thread-local storage used in CONFIG_SMP,
+ * due to the dependency on host_fs variable switch upon user/kernel
+ * context so, disable TLS until NOMMU supports SMP.
+ */
+#ifndef CONFIG_MMU
+#define __thread
+#endif
+
/*
* elf_aux.c
*/
diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig
index bdd7c8e39b01..f12e2e4e0a12 100644
--- a/arch/x86/um/Kconfig
+++ b/arch/x86/um/Kconfig
@@ -12,7 +12,7 @@ config UML_X86
select ARCH_USE_QUEUED_SPINLOCKS
select DCACHE_WORD_ACCESS
select HAVE_EFFICIENT_UNALIGNED_ACCESS
- select UML_SUBARCH_SUPPORTS_SMP if X86_CX8
+ select UML_SUBARCH_SUPPORTS_SMP if X86_CX8 && MMU
config 64BIT
bool "64-bit kernel" if "$(SUBARCH)" = "x86"
--
2.43.0
next prev parent reply other threads:[~2025-11-08 8:06 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-08 8:05 [PATCH v13 00/13] nommu UML Hajime Tazaki
2025-11-08 8:05 ` [PATCH v13 01/13] x86/um: nommu: elf loader for fdpic Hajime Tazaki
2025-11-08 8:05 ` [PATCH v13 02/13] um: decouple MMU specific code from the common part Hajime Tazaki
2025-11-08 8:05 ` [PATCH v13 03/13] um: nommu: memory handling Hajime Tazaki
2025-11-08 8:05 ` [PATCH v13 04/13] x86/um: nommu: syscall handling Hajime Tazaki
2025-11-08 8:05 ` [PATCH v13 05/13] um: nommu: seccomp syscalls hook Hajime Tazaki
2025-11-08 8:05 ` [PATCH v13 06/13] x86/um: nommu: process/thread handling Hajime Tazaki
2025-11-08 8:05 ` [PATCH v13 07/13] um: nommu: configure fs register on host syscall invocation Hajime Tazaki
2025-11-08 8:05 ` [PATCH v13 08/13] x86/um/vdso: nommu: vdso memory update Hajime Tazaki
2025-11-08 8:05 ` [PATCH v13 09/13] x86/um: nommu: signal handling Hajime Tazaki
2025-11-08 8:05 ` [PATCH v13 10/13] um: change machine name for uname output Hajime Tazaki
2025-11-08 8:05 ` Hajime Tazaki [this message]
2025-11-08 8:05 ` [PATCH v13 12/13] um: nommu: add documentation of nommu UML Hajime Tazaki
2025-11-08 8:05 ` [PATCH v13 13/13] um: nommu: plug nommu code into build system Hajime Tazaki
2025-11-10 9:14 ` [PATCH v13 00/13] nommu UML Christoph Hellwig
2025-11-10 12:18 ` Hajime Tazaki
2025-11-11 8:01 ` Johannes Berg
2025-11-12 8:52 ` Hajime Tazaki
2025-11-12 16:36 ` Tiwei Bie
2025-11-14 6:47 ` Hajime Tazaki
2025-11-25 9:58 ` Johannes Berg
2025-11-28 12:57 ` Hajime Tazaki
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