x86, setup: enable early console output from the decompressor

This enables the decompressor output to be seen on the serial console.
Most of the code is shared with the regular boot code.

We could add printf to the decompressor if needed, but currently there
is no sufficiently compelling user.

-v2: define BOOT_BOOT_H to avoid include boot.h
-v3: early_serial_base need to be static in misc.c ?
-v4: create seperate string.c printf.c cmdline.c early_serial_console.c
     after hpa's patch that allow global variables in compressed/misc stage
-v5: remove printf.c related

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 38 insertions, 0 deletions

diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
new file mode 100644
index 000000000000..a267849ac1c9
--- /dev/null
+++ b/arch/x86/boot/compressed/misc.h
@@ -0,0 +1,38 @@
+#ifndef BOOT_COMPRESSED_MISC_H
+#define BOOT_COMPRESSED_MISC_H
+
+/*
+ * we have to be careful, because no indirections are allowed here, and
+ * paravirt_ops is a kind of one. As it will only run in baremetal anyway,
+ * we just keep it from happening
+ */
+#undef CONFIG_PARAVIRT
+#ifdef CONFIG_X86_32
+#define _ASM_X86_DESC_H 1
+#endif
+
+#include <linux/linkage.h>
+#include <linux/screen_info.h>
+#include <linux/elf.h>
+#include <linux/io.h>
+#include <asm/page.h>
+#include <asm/boot.h>
+#include <asm/bootparam.h>
+
+#define BOOT_BOOT_H
+
+/* misc.c */
+extern struct boot_params *real_mode;           /* Pointer to real-mode data */
+void __putstr(int error, const char *s);
+#define putstr(__x)  __putstr(0, __x)
+#define puts(__x)  __putstr(0, __x)
+
+/* cmdline.c */
+int cmdline_find_option(const char *option, char *buffer, int bufsize);
+int cmdline_find_option_bool(const char *option);
+
+/* early_serial_console.c */
+extern int early_serial_base;
+void console_init(void);
+
+#endif