After commit a103f46633fd the kernel stopped compiling for several ARM32 platforms that I am building with a bare metal compiler. Bare metal compilers (arm-none-eabi-) don't define __linux__. This is because the header <acpi/platform/acenv.h> is now in the include path for <linux/irq.h>: CC arch/arm/kernel/irq.o CC kernel/sysctl.o CC crypto/api.o In file included from ../include/acpi/acpi.h:22, from ../include/linux/fw_table.h:29, from ../include/linux/acpi.h:18, from ../include/linux/irqchip.h:14, from ../arch/arm/kernel/irq.c:25: ../include/acpi/platform/acenv.h:218:2: error: #error Unknown target environment 218 | #error Unknown target environment | ^~~~~ One solution to make compilation with a bare metal compiler work again is to say the file is used with Linux from within the kernel if __KERNEL__ is defined so I did that. Fixes: a103f46633fd ("acpi: Move common tables helper functions to common lib") Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx> --- include/acpi/platform/acenv.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/acpi/platform/acenv.h b/include/acpi/platform/acenv.h index 337ffa931ee8..76444ffdc549 100644 --- a/include/acpi/platform/acenv.h +++ b/include/acpi/platform/acenv.h @@ -156,7 +156,7 @@ #endif -#if defined(_LINUX) || defined(__linux__) +#if defined(_LINUX) || defined(__linux__) || defined(__KERNEL__) #include <acpi/platform/aclinux.h> #elif defined(_APPLE) || defined(__APPLE__) --- base-commit: 9bacdd8996c77c42ca004440be610692275ff9d0 change-id: 20231113-arm-build-bug-ae543fd21199 Best regards, -- Linus Walleij <linus.walleij@xxxxxxxxxx>