vgacon: rework screen_info #ifdef checks

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.

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, though EFI apparently never uses
a framebuffer here.
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Khalid Aziz <khalid@gonehiking.org>
Acked-by: Helge Deller <deller@gmx.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20231009211845.3136536-3-arnd@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

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();
 }

arch/ia64/kernel/setup.c

@@ -86,9 +86,13 @@ 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;
+#endif
+#ifdef CONFIG_VGA_CONSOLE
 unsigned long vga_console_iobase;
 unsigned long vga_console_membase;
+#endif
 
 static struct resource data_resource = {
 	.name	= "Kernel data",
@@ -497,6 +501,7 @@ 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 +530,7 @@ 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

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);

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
 

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,

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;
 

arch/riscv/kernel/setup.c

@@ -40,15 +40,8 @@
 
 #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
 
 /*