Re: [06/12] arch: Declare screen_info in <asm/screen_info.h>

From: suijingfeng
Date: Fri Aug 18 2023 - 10:07:04 EST

Hi,


Why this patch get dropped in the end?

Since the global screen_info is an arch-specific thing,
Whenever an arch-neutral module or subsystem references the global screen_info,
There are some complaints from either compile testing robot.
Well, a programmer may handle it by using the CONFIG_SYSFB guard,
but it is not as precise as what this patch provided.

Personally, I think this patch is still valuable.
I suggest either forcing all other architectures to export screen_info,
like the X86 and IA64 arch does, after all the screen_info is a good thing.
or provide the fine-control version like this patch does.


On 2023/6/29 19:45, Thomas Zimmermann wrote:
The variable screen_info does not exist on all architectures. Declare
it in <asm-generic/screen_info.h>. All architectures that do declare it
will provide it via <asm/screen_info.h>.

Add the Kconfig token ARCH_HAS_SCREEN_INFO to guard against access on
architectures that don't provide screen_info.

Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Cc: Richard Henderson <richard.henderson@xxxxxxxxxx>
Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>
Cc: Matt Turner <mattst88@xxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Guo Ren <guoren@xxxxxxxxxx>
Cc: Brian Cain <bcain@xxxxxxxxxxx>
Cc: Huacai Chen <chenhuacai@xxxxxxxxxx>
Cc: WANG Xuerui <kernel@xxxxxxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: Dinh Nguyen <dinguyen@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx>
Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
Cc: Rich Felker <dalias@xxxxxxxx>
Cc: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Chris Zankel <chris@xxxxxxxxxx>
Cc: Max Filippov <jcmvbkbc@xxxxxxxxx>
Cc: Helge Deller <deller@xxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
Cc: Juerg Haefliger <juerg.haefliger@xxxxxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
Cc: "Russell King (Oracle)" <rmk+kernel@xxxxxxxxxxxxxxx>
Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
Cc: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>
Cc: "Mike Rapoport (IBM)" <rppt@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Acked-by: WANG Xuerui <git@xxxxxxxxxx> # loongarch
---
arch/Kconfig | 6 ++++++
arch/alpha/Kconfig | 1 +
arch/arm/Kconfig | 1 +
arch/arm64/Kconfig | 1 +
arch/csky/Kconfig | 1 +
arch/hexagon/Kconfig | 1 +
arch/ia64/Kconfig | 1 +
arch/loongarch/Kconfig | 1 +
arch/mips/Kconfig | 1 +
arch/nios2/Kconfig | 1 +
arch/powerpc/Kconfig | 1 +
arch/riscv/Kconfig | 1 +
arch/sh/Kconfig | 1 +
arch/sparc/Kconfig | 1 +
arch/x86/Kconfig | 1 +
arch/xtensa/Kconfig | 1 +
drivers/video/Kconfig | 3 +++
include/asm-generic/Kbuild | 1 +
include/asm-generic/screen_info.h | 12 ++++++++++++
include/linux/screen_info.h | 2 +-
20 files changed, 38 insertions(+), 1 deletion(-)
create mode 100644 include/asm-generic/screen_info.h

diff --git a/arch/Kconfig b/arch/Kconfig
index 205fd23e0cada..2f58293fd7bcb 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1466,6 +1466,12 @@ config ARCH_HAS_NONLEAF_PMD_YOUNG
address translations. Page table walkers that clear the accessed bit
may use this capability to reduce their search space.
+config ARCH_HAS_SCREEN_INFO
+ bool
+ help
+ Selected by architectures that provide a global instance of
+ screen_info.
+
source "kernel/gcov/Kconfig"
source "scripts/gcc-plugins/Kconfig"
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index a5c2b1aa46b02..d749011d88b14 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -4,6 +4,7 @@ config ALPHA
default y
select ARCH_32BIT_USTAT_F_TINODE
select ARCH_HAS_CURRENT_STACK_POINTER
+ select ARCH_HAS_SCREEN_INFO
select ARCH_MIGHT_HAVE_PC_PARPORT
select ARCH_MIGHT_HAVE_PC_SERIO
select ARCH_NO_PREEMPT
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 0fb4b218f6658..a9d01ee67a90e 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -15,6 +15,7 @@ config ARM
select ARCH_HAS_MEMBARRIER_SYNC_CORE
select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
select ARCH_HAS_PTE_SPECIAL if ARM_LPAE
+ select ARCH_HAS_SCREEN_INFO
select ARCH_HAS_SETUP_DMA_OPS
select ARCH_HAS_SET_MEMORY
select ARCH_STACKWALK
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 343e1e1cae10a..21addc4715bb3 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -36,6 +36,7 @@ config ARM64
select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
select ARCH_HAS_PTE_DEVMAP
select ARCH_HAS_PTE_SPECIAL
+ select ARCH_HAS_SCREEN_INFO
select ARCH_HAS_SETUP_DMA_OPS
select ARCH_HAS_SET_DIRECT_MAP
select ARCH_HAS_SET_MEMORY
diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 4df1f8c9d170b..28444e581fc1f 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -10,6 +10,7 @@ config CSKY
select ARCH_USE_QUEUED_RWLOCKS
select ARCH_USE_QUEUED_SPINLOCKS
select ARCH_HAS_CURRENT_STACK_POINTER
+ select ARCH_HAS_SCREEN_INFO
select ARCH_INLINE_READ_LOCK if !PREEMPTION
select ARCH_INLINE_READ_LOCK_BH if !PREEMPTION
select ARCH_INLINE_READ_LOCK_IRQ if !PREEMPTION
diff --git a/arch/hexagon/Kconfig b/arch/hexagon/Kconfig
index 54eadf2651786..cc683c0a43d34 100644
--- a/arch/hexagon/Kconfig
+++ b/arch/hexagon/Kconfig
@@ -5,6 +5,7 @@ comment "Linux Kernel Configuration for Hexagon"
config HEXAGON
def_bool y
select ARCH_32BIT_OFF_T
+ select ARCH_HAS_SCREEN_INFO
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
select ARCH_NO_PREEMPT
select DMA_GLOBAL_POOL
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index e79f15e32a451..8b1e785e6d53d 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -10,6 +10,7 @@ config IA64
bool
select ARCH_BINFMT_ELF_EXTRA_PHDRS
select ARCH_HAS_DMA_MARK_CLEAN
+ select ARCH_HAS_SCREEN_INFO
select ARCH_HAS_STRNCPY_FROM_USER
select ARCH_HAS_STRNLEN_USER
select ARCH_MIGHT_HAVE_PC_PARPORT
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index d38b066fc931b..6aab2fb7753da 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -13,6 +13,7 @@ config LOONGARCH
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
select ARCH_HAS_PTE_SPECIAL
+ select ARCH_HAS_SCREEN_INFO
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_INLINE_READ_LOCK if !PREEMPTION
select ARCH_INLINE_READ_LOCK_BH if !PREEMPTION
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 675a8660cb85a..c0ae09789cb6d 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -10,6 +10,7 @@ config MIPS
select ARCH_HAS_KCOV
select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE if !EVA
select ARCH_HAS_PTE_SPECIAL if !(32BIT && CPU_HAS_RIXI)
+ select ARCH_HAS_SCREEN_INFO
select ARCH_HAS_STRNCPY_FROM_USER
select ARCH_HAS_STRNLEN_USER
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
diff --git a/arch/nios2/Kconfig b/arch/nios2/Kconfig
index e5936417d3cd3..7183eea282212 100644
--- a/arch/nios2/Kconfig
+++ b/arch/nios2/Kconfig
@@ -3,6 +3,7 @@ config NIOS2
def_bool y
select ARCH_32BIT_OFF_T
select ARCH_HAS_DMA_PREP_COHERENT
+ select ARCH_HAS_SCREEN_INFO
select ARCH_HAS_SYNC_DMA_FOR_CPU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
select ARCH_HAS_DMA_SET_UNCACHED
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index bff5820b7cda1..b1acad3076180 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -148,6 +148,7 @@ config PPC
select ARCH_HAS_PTE_DEVMAP if PPC_BOOK3S_64
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE && PPC_BOOK3S_64
+ select ARCH_HAS_SCREEN_INFO
select ARCH_HAS_SET_MEMORY
select ARCH_HAS_STRICT_KERNEL_RWX if (PPC_BOOK3S || PPC_8xx || 40x) && !HIBERNATION
select ARCH_HAS_STRICT_KERNEL_RWX if PPC_85xx && !HIBERNATION && !RANDOMIZE_BASE
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 5966ad97c30c3..b5a48f8424af9 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -29,6 +29,7 @@ config RISCV
select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
select ARCH_HAS_PMEM_API
select ARCH_HAS_PTE_SPECIAL
+ select ARCH_HAS_SCREEN_INFO
select ARCH_HAS_SET_DIRECT_MAP if MMU
select ARCH_HAS_SET_MEMORY if MMU
select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 04b9550cf0070..001f5149952b4 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -10,6 +10,7 @@ config SUPERH
select ARCH_HAS_GIGANTIC_PAGE
select ARCH_HAS_GCOV_PROFILE_ALL
select ARCH_HAS_PTE_SPECIAL
+ select ARCH_HAS_SCREEN_INFO
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_HIBERNATION_POSSIBLE if MMU
select ARCH_MIGHT_HAVE_PC_PARPORT
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 8535e19062f65..e4bfb80b48cfe 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -13,6 +13,7 @@ config 64BIT
config SPARC
bool
default y
+ select ARCH_HAS_SCREEN_INFO
select ARCH_MIGHT_HAVE_PC_PARPORT if SPARC64 && PCI
select ARCH_MIGHT_HAVE_PC_SERIO
select DMA_OPS
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 53bab123a8ee4..d7c2bf4ee403d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -91,6 +91,7 @@ config X86
select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
select ARCH_HAS_COPY_MC if X86_64
+ select ARCH_HAS_SCREEN_INFO
select ARCH_HAS_SET_MEMORY
select ARCH_HAS_SET_DIRECT_MAP
select ARCH_HAS_STRICT_KERNEL_RWX
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 3c6e5471f025b..c6cbd7459939c 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -8,6 +8,7 @@ config XTENSA
select ARCH_HAS_DMA_PREP_COHERENT if MMU
select ARCH_HAS_GCOV_PROFILE_ALL
select ARCH_HAS_KCOV
+ select ARCH_HAS_SCREEN_INFO
select ARCH_HAS_SYNC_DMA_FOR_CPU if MMU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE if MMU
select ARCH_HAS_DMA_SET_UNCACHED if MMU
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 8b2b9ac37c3df..d4a72bea56be0 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -21,6 +21,9 @@ config STI_CORE
config VIDEO_CMDLINE
bool
+config ARCH_HAS_SCREEN_INFO
+ bool
+
config VIDEO_NOMODESET
bool
default n
diff --git a/include/asm-generic/Kbuild b/include/asm-generic/Kbuild
index 941be574bbe00..5e5d4158a4b4b 100644
--- a/include/asm-generic/Kbuild
+++ b/include/asm-generic/Kbuild
@@ -47,6 +47,7 @@ mandatory-y += percpu.h
mandatory-y += pgalloc.h
mandatory-y += preempt.h
mandatory-y += rwonce.h
+mandatory-y += screen_info.h
mandatory-y += sections.h
mandatory-y += serial.h
mandatory-y += shmparam.h
diff --git a/include/asm-generic/screen_info.h b/include/asm-generic/screen_info.h
new file mode 100644
index 0000000000000..6fd0e50fabfcd
--- /dev/null
+++ b/include/asm-generic/screen_info.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _ASM_GENERIC_SCREEN_INFO_H
+#define _ASM_GENERIC_SCREEN_INFO_H
+
+#include <uapi/linux/screen_info.h>
+
+#if defined(CONFIG_ARCH_HAS_SCREEN_INFO)
+extern struct screen_info screen_info;
+#endif
+
+#endif /* _ASM_GENERIC_SCREEN_INFO_H */
diff --git a/include/linux/screen_info.h b/include/linux/screen_info.h
index eab7081392d50..c764b9a51c24b 100644
--- a/include/linux/screen_info.h
+++ b/include/linux/screen_info.h
@@ -4,6 +4,6 @@
#include <uapi/linux/screen_info.h>
-extern struct screen_info screen_info;
+#include <asm/screen_info.h>
#endif /* _SCREEN_INFO_H */