[PATCH 2/4] vgacon: rework screen_info #ifdef checks

[PATCH 2/4] vgacon: rework screen_info #ifdef checks

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

On non-x86 architectures, the screen_info variable is generally only
used for the VGA console where supported, and in some cases the EFI
framebuffer or vga16fb.

Now that we have a definite list of which architectures actually use it
for what, use consistent #ifdef checks so the global variable is only
defined when it is actually used on those architectures.

On powerpc, there is no support for vgacon, but there is support for
vga16fb. Loongarch and riscv have no support for vgacon or vga16fb, but
they support EFI firmware, so only that needs to be checked, and the
initialization can be removed because that is handled by EFI.
IA64 has both vgacon and EFI.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/alpha/kernel/setup.c          |  2 ++
 arch/alpha/kernel/sys_sio.c        |  2 ++
 arch/ia64/kernel/setup.c           |  4 ++++
 arch/loongarch/kernel/setup.c      |  2 ++
 arch/mips/jazz/setup.c             |  2 +-
 arch/mips/kernel/setup.c           |  2 +-
 arch/mips/sibyte/swarm/setup.c     |  2 +-
 arch/mips/sni/setup.c              |  2 +-
 arch/powerpc/kernel/setup-common.c |  2 +-
 arch/riscv/kernel/setup.c          | 11 ++---------
 10 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/arch/alpha/kernel/setup.c b/arch/alpha/kernel/setup.c
index b650ff1cb022e..b4d2297765c02 100644
--- a/arch/alpha/kernel/setup.c
+++ b/arch/alpha/kernel/setup.c
@@ -131,6 +131,7 @@ static void determine_cpu_caches (unsigned int);
 
 static char __initdata command_line[COMMAND_LINE_SIZE];
 
+#ifdef CONFIG_VGA_CONSOLE
 /*
  * The format of "screen_info" is strange, and due to early
  * i386-setup code. This is just enough to make the console
@@ -147,6 +148,7 @@ struct screen_info screen_info = {
 };
 
 EXPORT_SYMBOL(screen_info);
+#endif
 
 /*
  * The direct map I/O window, if any.  This should be the same
diff --git a/arch/alpha/kernel/sys_sio.c b/arch/alpha/kernel/sys_sio.c
index 7c420d8dac53d..7de8a5d2d2066 100644
--- a/arch/alpha/kernel/sys_sio.c
+++ b/arch/alpha/kernel/sys_sio.c
@@ -57,11 +57,13 @@ sio_init_irq(void)
 static inline void __init
 alphabook1_init_arch(void)
 {
+#ifdef CONFIG_VGA_CONSOLE
 	/* The AlphaBook1 has LCD video fixed at 800x600,
 	   37 rows and 100 cols. */
 	screen_info.orig_y = 37;
 	screen_info.orig_video_cols = 100;
 	screen_info.orig_video_lines = 37;
+#endif
 
 	lca_init_arch();
 }
diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index 5a55ac82c13a4..0c09ff7fde46b 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -86,9 +86,11 @@ EXPORT_SYMBOL(local_per_cpu_offset);
 #endif
 unsigned long ia64_cycles_per_usec;
 struct ia64_boot_param *ia64_boot_param;
+#if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_EFI)
 struct screen_info screen_info;
 unsigned long vga_console_iobase;
 unsigned long vga_console_membase;
+#endif
 
 static struct resource data_resource = {
 	.name	= "Kernel data",
@@ -497,6 +499,7 @@ early_console_setup (char *cmdline)
 static void __init
 screen_info_setup(void)
 {
+#ifdef CONFIG_VGA_CONSOLE
 	unsigned int orig_x, orig_y, num_cols, num_rows, font_height;
 
 	memset(&screen_info, 0, sizeof(screen_info));
@@ -525,6 +528,7 @@ screen_info_setup(void)
 	screen_info.orig_video_mode = 3;	/* XXX fake */
 	screen_info.orig_video_isVGA = 1;	/* XXX fake */
 	screen_info.orig_video_ega_bx = 3;	/* XXX fake */
+#endif
 }
 
 static inline void
diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 78a00359bde3c..6b3932677f5de 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -57,7 +57,9 @@
 #define SMBIOS_CORE_PACKAGE_OFFSET	0x23
 #define LOONGSON_EFI_ENABLE		(1 << 3)
 
+#ifdef CONFIG_EFI
 struct screen_info screen_info __section(".data");
+#endif
 
 unsigned long fw_arg0, fw_arg1, fw_arg2;
 DEFINE_PER_CPU(unsigned long, kernelsp);
diff --git a/arch/mips/jazz/setup.c b/arch/mips/jazz/setup.c
index ee044261eb223..3c14548353e47 100644
--- a/arch/mips/jazz/setup.c
+++ b/arch/mips/jazz/setup.c
@@ -76,7 +76,7 @@ void __init plat_mem_setup(void)
 
 	_machine_restart = jazz_machine_restart;
 
-#ifdef CONFIG_VT
+#ifdef CONFIG_VGA_CONSOLE
 	screen_info = (struct screen_info) {
 		.orig_video_cols	= 160,
 		.orig_video_lines	= 64,
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index cb871eb784a7c..1aba7dc95132c 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -54,7 +54,7 @@ struct cpuinfo_mips cpu_data[NR_CPUS] __read_mostly;
 
 EXPORT_SYMBOL(cpu_data);
 
-#ifdef CONFIG_VT
+#ifdef CONFIG_VGA_CONSOLE
 struct screen_info screen_info;
 #endif
 
diff --git a/arch/mips/sibyte/swarm/setup.c b/arch/mips/sibyte/swarm/setup.c
index 76683993cdd3a..37df504d3ecbb 100644
--- a/arch/mips/sibyte/swarm/setup.c
+++ b/arch/mips/sibyte/swarm/setup.c
@@ -129,7 +129,7 @@ void __init plat_mem_setup(void)
 	if (m41t81_probe())
 		swarm_rtc_type = RTC_M41T81;
 
-#ifdef CONFIG_VT
+#ifdef CONFIG_VGA_CONSOLE
 	screen_info = (struct screen_info) {
 		.orig_video_page	= 52,
 		.orig_video_mode	= 3,
diff --git a/arch/mips/sni/setup.c b/arch/mips/sni/setup.c
index efad85c8c823b..9984cf91be7d0 100644
--- a/arch/mips/sni/setup.c
+++ b/arch/mips/sni/setup.c
@@ -38,7 +38,7 @@ extern void sni_machine_power_off(void);
 
 static void __init sni_display_setup(void)
 {
-#if defined(CONFIG_VT) && defined(CONFIG_VGA_CONSOLE) && defined(CONFIG_FW_ARC)
+#if defined(CONFIG_VGA_CONSOLE) && defined(CONFIG_FW_ARC)
 	struct screen_info *si = &screen_info;
 	DISPLAY_STATUS *di;
 
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index d2a446216444f..b717875a12a9a 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -98,6 +98,7 @@ int boot_cpu_hwid = -1;
 int dcache_bsize;
 int icache_bsize;
 
+#if IS_ENABLED(CONFIG_FB_VGA16)
 /*
  * This still seems to be needed... -- paulus
  */ 
@@ -109,7 +110,6 @@ struct screen_info screen_info = {
 	.orig_video_isVGA = 1,
 	.orig_video_points = 16
 };
-#if defined(CONFIG_FB_VGA16_MODULE)
 EXPORT_SYMBOL(screen_info);
 #endif
 
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 971fe776e2f8b..a3dbe13f45fb3 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -39,15 +39,8 @@
 
 #include "head.h"
 
-#if defined(CONFIG_DUMMY_CONSOLE) || defined(CONFIG_EFI)
-struct screen_info screen_info __section(".data") = {
-	.orig_video_lines	= 30,
-	.orig_video_cols	= 80,
-	.orig_video_mode	= 0,
-	.orig_video_ega_bx	= 0,
-	.orig_video_isVGA	= 1,
-	.orig_video_points	= 8
-};
+#if defined(CONFIG_EFI)
+struct screen_info screen_info __section(".data");
 #endif
 
 /*
-- 
2.39.2

Re: [PATCH 2/4] vgacon: rework screen_info #ifdef checks

[Javier Martinez Canillas]

Arnd Bergmann <arnd@kernel.org> writes:

> From: Arnd Bergmann <arnd@arndb.de>
>
> On non-x86 architectures, the screen_info variable is generally only
> used for the VGA console where supported, and in some cases the EFI
> framebuffer or vga16fb.
>
> Now that we have a definite list of which architectures actually use it
> for what, use consistent #ifdef checks so the global variable is only
> defined when it is actually used on those architectures.
>
> On powerpc, there is no support for vgacon, but there is support for
> vga16fb. Loongarch and riscv have no support for vgacon or vga16fb, but
> they support EFI firmware, so only that needs to be checked, and the
> initialization can be removed because that is handled by EFI.
> IA64 has both vgacon and EFI.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---

[...]

> diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
> index 5a55ac82c13a4..0c09ff7fde46b 100644
> --- a/arch/ia64/kernel/setup.c
> +++ b/arch/ia64/kernel/setup.c
> @@ -86,9 +86,11 @@ EXPORT_SYMBOL(local_per_cpu_offset);
>  #endif
>  unsigned long ia64_cycles_per_usec;
>  struct ia64_boot_param *ia64_boot_param;
> +#if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_EFI)
>  struct screen_info screen_info;

I think that only screen_info should be guarded by both symbols ?

>  unsigned long vga_console_iobase;

It seems this variable was never used since it was introduced by commit
66b7f8a30437 ("[IA64-SGI] pcdp: add PCDP pci interface support") ?

>  unsigned long vga_console_membase;

And this is only used by mdacon (not supported by ia64), vgacon and
vga16fb (not supported by ia64 either).

So this could just be guarded just by CONFIG_VGA_CONSOLE for ia64 ?

The rest of the patch looks good to me.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat

Re: [PATCH 2/4] vgacon: rework screen_info #ifdef checks

[Arnd Bergmann]

On Fri, Jul 7, 2023, at 15:40, Javier Martinez Canillas wrote:
>> diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
>> index 5a55ac82c13a4..0c09ff7fde46b 100644
>> --- a/arch/ia64/kernel/setup.c
>> +++ b/arch/ia64/kernel/setup.c
>> @@ -86,9 +86,11 @@ EXPORT_SYMBOL(local_per_cpu_offset);
>>  #endif
>>  unsigned long ia64_cycles_per_usec;
>>  struct ia64_boot_param *ia64_boot_param;
>> +#if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_EFI)
>>  struct screen_info screen_info;
>
> I think that only screen_info should be guarded by both symbols ?
>
>>  unsigned long vga_console_iobase;
>
> It seems this variable was never used since it was introduced by commit
> 66b7f8a30437 ("[IA64-SGI] pcdp: add PCDP pci interface support") ?
>
>>  unsigned long vga_console_membase;
>
> And this is only used by mdacon (not supported by ia64), vgacon and
> vga16fb (not supported by ia64 either).
>
> So this could just be guarded just by CONFIG_VGA_CONSOLE for ia64 ?

Right, I though about doing this more accurately, but in the end
went for the simplest change rather than spending much more time
trying to clean up the unused variables etc.

Let me know if you'd prefer me to respin this part, otherwise
I'd call the ia64 bit good enough for the purpose of the series.

     Arnd

Re: [PATCH 2/4] vgacon: rework screen_info #ifdef checks

[Javier Martinez Canillas]

"Arnd Bergmann" <arnd@arndb.de> writes:

> On Fri, Jul 7, 2023, at 15:40, Javier Martinez Canillas wrote:

[...]

>> And this is only used by mdacon (not supported by ia64), vgacon and
>> vga16fb (not supported by ia64 either).
>>
>> So this could just be guarded just by CONFIG_VGA_CONSOLE for ia64 ?
>
> Right, I though about doing this more accurately, but in the end
> went for the simplest change rather than spending much more time
> trying to clean up the unused variables etc.
>
> Let me know if you'd prefer me to respin this part, otherwise
> I'd call the ia64 bit good enough for the purpose of the series.
>

No need to re-spin, agreed that makes sense to keep it simpler.

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat

Re: [PATCH 2/4] vgacon: rework screen_info #ifdef checks

[Thomas Bogendoerfer]

On Fri, Jul 07, 2023 at 11:52:24AM +0200, Arnd Bergmann wrote:
> diff --git a/arch/mips/jazz/setup.c b/arch/mips/jazz/setup.c
> index ee044261eb223..3c14548353e47 100644
> --- a/arch/mips/jazz/setup.c
> +++ b/arch/mips/jazz/setup.c
> @@ -76,7 +76,7 @@ void __init plat_mem_setup(void)
>  
>  	_machine_restart = jazz_machine_restart;
>  
> -#ifdef CONFIG_VT
> +#ifdef CONFIG_VGA_CONSOLE
>  	screen_info = (struct screen_info) {
>  		.orig_video_cols	= 160,
>  		.orig_video_lines	= 64,

that wssn't intended for VGA but for fbdev/g364fb, which doesn't use
it. So removing it is probably the best thing.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]