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Subject[PATCH v3] x86: Do not write into VGA memory space if there is no VGA device in the system
Date
Ensure that early_printk() does not write into VGA memory space
if there is not VGA device in the system.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
---
v3:
Changes are now limited to early_printk.c. Functionality is retained, meaning
there will still be output on the VGA console before setup_early_printk()
is called, but only if a VGA device is known to exist in the system.

arch/x86/kernel/early_printk.c | 17 +++++++++++++----
1 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index b9c830c..783cb25 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -170,10 +170,13 @@ asmlinkage void early_printk(const char *fmt, ...)
int n;
va_list ap;

- va_start(ap, fmt);
- n = vscnprintf(buf, sizeof(buf), fmt, ap);
- early_console->write(early_console, buf, n);
- va_end(ap);
+ if (early_console && (early_console_initialized ||
+ boot_params.screen_info.orig_video_isVGA == 1)) {
+ va_start(ap, fmt);
+ n = vscnprintf(buf, sizeof(buf), fmt, ap);
+ early_console->write(early_console, buf, n);
+ va_end(ap);
+ }
}

static inline void early_console_register(struct console *con, int keep_early)
@@ -233,6 +236,12 @@ static int __init setup_early_printk(char *buf)
#endif
buf++;
}
+
+ /* If there is no VGA device, don't try to use it as early console. */
+ if (early_console == &early_vga_console &&
+ boot_params.screen_info.orig_video_isVGA != 1)
+ early_console = NULL;
+
return 0;
}

--
1.7.0.87.g0901d


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