[Xen-devel] [PATCH v2 1/2] x86/boot: fix early error display

[Doug Goldstein <cardoe@xxxxxxxxxx>]

From: David Esler <drumandstrum@xxxxxxxxx>

In 9180f5365524 a change was made to the send_chr function to take in
C-strings and print out a character at a time until a NULL was
encountered. However there is no code to increment the current character
position resulting in an endless loop of the first character. This adds
a simple increment.

Reviewed-by: Doug Goldstein <cardoe@xxxxxxxxxx>
Signed-off-by: David Esler <drumandstrum@xxxxxxxxx>
---
 xen/arch/x86/boot/head.S | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index fd6fc337fe..9cc35da558 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -173,10 +173,11 @@ not_multiboot:
 .Lget_vtb:
         mov     sym_esi(vga_text_buffer),%edi
 .Lsend_chr:
-        mov     (%esi),%bl
-        test    %bl,%bl        # Terminate on '\0' sentinel
+        lodsb
+        test    %al,%al        # Terminate on '\0' sentinel
         je      .Lhalt
         mov     $0x3f8+5,%dx   # UART Line Status Register
+        mov     %al,%bl
 2:      in      %dx,%al
         test    $0x20,%al      # Test THR Empty flag
         je      2b
@@ -185,7 +186,7 @@ not_multiboot:
         out     %al,%dx        # Send a character over the serial line
         test    %edi,%edi      # Is the VGA text buffer available?
         jz      .Lsend_chr
-        movsb                  # Write a character to the VGA text buffer
+        stosb                  # Write a character to the VGA text buffer
         mov     $7,%al
         stosb                  # Write an attribute to the VGA text buffer
         jmp     .Lsend_chr
-- 
2.13.5


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