Changeset 76c356f in rtems for c/src/lib/libbsp/i386/pc386/start/start16.S

Timestamp:

12/03/99 15:46:17 (24 years ago)

Author:

Joel Sherrill <joel.sherrill@…>

Branches:

4.10, 4.11, 4.8, 4.9, 5, master

Children:

a548c8a5

Parents:

1e4a7d4

Message:

Patch from Aleksey (Quality Quorum <qqi@…>) to change the
delay loop in this BSP. Here is his response to a question about
the patch:

Yes, or that other machine has a different chipset with different
timing requirements on enabling Gate 20. I am strongly suspecting
that it may some how related to the video card I am using (on my
old P-75 target it was plain PCI VGA, on my new one it is Diamond Stealth
3D 2000).

File:

• c/src/lib/libbsp/i386/pc386/start/start16.S (modified) (3 diffs)

c/src/lib/libbsp/i386/pc386/start/start16.S

@@ -116 +116 @@
         call    empty_8042
 
+        call    delay
+        call    delay
+        call    delay
+
         movl    %cs:HDRSTART + HDROFF, %eax     #
         pushl   %eax                            # jump to start of 32 bit code
@@ -123 +127 @@
 | delay
 +------------------------------------------------------------------------------
-| Delay is needed after doing I/O. We do it by writing to a non-existent port.
-+----------------------------------------------------------------------------*/
+| Delay is needed after doing I/O. 
+|
+| The outb version is OK on most machines BUT the loop version ...
+| 
+| will delay for 1us on 1Gz machine, it will take a little bit
+| longer on slower machines, however, it does not matter because we
+| are going to call this function only a few times
+
++----------------------------------------------------------------------------*/
+        .p2align 4
         .globl _delay
         .globl delay
 delay:
 _delay:
-        outb    %al, $0xED      # about 1uS delay
+/*
+        outb    %al, $0xED      # about 1uS delay on most machines
+*/
+/*
+ 
+        movl    $0x200, %eax
+delay1:
+        dec     %eax
+        jnz     delay1
         ret
 
@@ -140 +160 @@
 | and we probably couldn't proceed anyway.
 +----------------------------------------------------------------------------*/
+        .p2align 4
         .globl _empty_8042
         .globl empty_8042