Mailing List Archive

Patch to vesamenu.c32 from Syslinux 3.51
I was having a display problem with memtest86 and dos via a memdisk
image not displaying properly when launched using vesamenu.c32 and using
a PNG background image. Instead of proper text output the display mode
is not changed and the existing menu image is corrupted by the outputted
text. This seems to be similar or identical to a problem describe in a
previous mailing:
http://syslinux.zytor.com/archives/2007-May/008442.html

Many kernels and OS seem to assume the display will still be in text
mode and do not change the video mode prior to writing text. After
launching these kernels create corruption in the existing displayed
image and/or make it appear as though the system is hung while the
underlying kernel starts. This patch changes the video mode back to a
text mode before launching the kernel allowing the display to properly
render for those apps that don't set the display mode before writing:

--- menumain.orig 2007-09-27 16:27:45.000000000 -0700
+++ menumain.c 2007-09-27 16:27:30.000000000 -0700
@@ -1036,6 +1036,8 @@
} else {
if (type < KT_KERNEL)
type = KT_KERNEL;
+ ireg.eax.w[0]= 0x0003; /* Return to text mode */
+ __intcall(0x10, &ireg, NULL);
ireg.eax.w[0] = 0x0016; /* Run kernel image */
ireg.esi.w[0] = OFFS(kernel);
ireg.ds = SEG(kernel);

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Re: Patch to vesamenu.c32 from Syslinux 3.51 [ In reply to ]
Collins, Jeremy wrote:
> I was having a display problem with memtest86 and dos via a memdisk
> image not displaying properly when launched using vesamenu.c32 and using
> a PNG background image. Instead of proper text output the display mode
> is not changed and the existing menu image is corrupted by the outputted
> text. This seems to be similar or identical to a problem describe in a
> previous mailing:
> http://syslinux.zytor.com/archives/2007-May/008442.html
>
> Many kernels and OS seem to assume the display will still be in text
> mode and do not change the video mode prior to writing text. After
> launching these kernels create corruption in the existing displayed
> image and/or make it appear as though the system is hung while the
> underlying kernel starts. This patch changes the video mode back to a
> text mode before launching the kernel allowing the display to properly
> render for those apps that don't set the display mode before writing:
>

A better patch for this should already be in 3.52.

-hpa

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