qemu fails to scroll screen on ^Vidmem output

Pascal uses ^Vidmem for B800 console output. The terminal does not oblige the Pascal OS code to scroll the output. Virtualbox emulation works, so this must be a qemu bug. Using QEMU in KVM mode as Ubuntu LTS.

Source line to trip bug(in theory pushes VideoMem up one line):

procedure Scroll;
//this is whats causing crashes. FIXME:Virtualbox not affected.QEMU BUG?
begin
  if scrolldisabled then exit;
      if (CursorPosY >= 24) then begin  //in case called before end of screen
    blank:= $20 or (TextAttr shl 8);
    Move((VidMem+(2*80))^,VidMem^,24*(2*80));
    // Empty last line
    FillWord((VidMem+(24*2*80))^,80,Blank);
    CursorPosX:=1;
    CursorPosY:=23;
    update_cursor;
  end;
end;

Thanks for reporting this bug.  Is there any other reproducer you can give us?

I dont know how to write it myself, but the original kernel scrolling 
code is in C.
Might try OSDev forums. Not that I know of.

On 11/27/2013 09:24 PM, Serge Hallyn wrote:
> Thanks for reporting this bug.  Is there any other reproducer you can
> give us?
>
> ** No longer affects: kvm (Ubuntu)
>
> ** Also affects: qemu (Ubuntu)
>     Importance: Undecided
>         Status: New
>
> ** Changed in: qemu (Ubuntu)
>         Status: New => Incomplete
>
> ** Changed in: qemu
>         Status: New => Incomplete
>



Can you test with the latest version to see if this still affects you?
If this still is a problem, any information on how to obtain the Guest OS in question that would also be helpful.

It is hosted on google code, a dying service. FreePascal(coffee) OS.A 
more basic version is posted there.I assume it works as the version that 
I last built did not for some reason. Sources should be there via 
subversion checkout.Thats what I tested with.
https://code.google.com/p/coffee-os/

  It uses a basic VRAM scroll buffer and writes to it.

Examples are found elsewhere in C. (OS Dev pages)
Im in the middle of a fedup upgrade at the moment, but will see what I 
can do.

On 06/17/2015 12:11 PM, Chris J Arges wrote:
> Can you test with the latest version to see if this still affects you?
> If this still is a problem, any information on how to obtain the Guest OS in question that would also be helpful.
>
> ** Changed in: qemu (Ubuntu)
>         Status: New => Incomplete
>



Triaging old bug tickets... can you still reproduce this issue with the latest version of QEMU? Or could we close this ticket nowadays?

[Expired for QEMU because there has been no activity for 60 days.]

[Expired for qemu (Ubuntu) because there has been no activity for 60 days.]