Hello,
Over here I'm trying to USB boot gPXE.
On some computers I'm able to achieve that
and this E-mail is about computer model that says "no boot device".
To find the root cause of that problem,
have I the need for an early print routine.
So it is possible "to trace" execution of gPXE with print statements.
Like the 'kprintf()' in the Linux kernel.
Printing single characters do I with INT 0x10.
Printing strings fails.
This is what I currently have:
diff --git a/src/arch/i386/prefix/mbr.S b/src/arch/i386/prefix/mbr.S
index adfe204..c1408f1 100644
--- a/src/arch/i386/prefix/mbr.S
+++ b/src/arch/i386/prefix/mbr.S
@@ -5,6 +5,7 @@
.org 0
mbr:
+#include "earlyhello.S"
movw $exec_sector, %bp
jmp find_active_partition
exec_sector:
diff --git a/src/arch/i386/prefix/earlyhello.S
b/src/arch/i386/prefix/earlyhello.S
new file mode 100644
index 0000000..45424a5
--- /dev/null
+++ b/src/arch/i386/prefix/earlyhello.S
@@ -0,0 +1,32 @@
+FILE_LICENCE ( GPL2_OR_LATER )
+
+ .text
+ .arch i386
+ .section ".prefix", "awx", @progbits
+ .code16
+
+ /* Print message */
+ movb $0x0e, %ah
+ movb $'G', %al
+ int $0x10
+ movb $'o', %al
+ int $0x10
+ movb $'o', %al
+ int $0x10
+ movb $'d', %al
+ int $0x10
+
+ movw $text, %si
+ jmp early_hello
+text: .asciz "morning\r\n"
+early_hello:
+ cld
+ movw $0x0007, %bx
+ movb $0x0e, %ah
+1: lodsb
+ testb %al, %al
+ je 99f
+ int $0x10
+ jmp 1b
+99:
+/* last line */
It prints 'Good???', where '???' are non-ASCII characters
and 'Goodmorning
' is what is wanted.
What should I do to "early print strings"?
Cheers
Geert Stappers
_______________________________________________
gPXE mailing list
[email protected]
http://etherboot.org/mailman/listinfo/gpxe
