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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.]
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