On 10/03/2017 16:54, Herbie Robinson wrote: > Fix Bug #1670509: wrong video attrs for int 10h, ah==13h > The subroutine set_cursor_position is trashing %bx. > Unfortunately, %bl contains the video attribute for write_string. > > The fix saves %bx in the function prolog and restores it in > the epilog. > > Signed-off-by: Herbie Robinson <herbie.robin...@stratus.com>
Reviewed-by: Laurent Vivier <lviv...@redhat.com> > --- > Removed incorrect code deletions from set_current_cursor. > Removed explanation of same from the commit message. > > BTW, I didn't see any test cases for this code, but if they exist > and somebody points me at them, I should be able to generate a > very small qcow2 file that demonstrates the problem. > > sgabios.S | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/sgabios.S b/sgabios.S > index 275d063..96c4e23 100644 > --- a/sgabios.S > +++ b/sgabios.S > @@ -1728,6 +1728,7 @@ write_string_tail: > > set_cursor_position: > pushw %ax > + pushw %bx > pushw %ds > pushw $BDA_SEG > popw %ds /* ds = 0x40 */ > @@ -1738,6 +1739,7 @@ set_cursor_position: > movw %ax, %bx /* bx = cursor save offset */ > movw %dx, (%bx) /* save new cursor value */ > popw %ds > + popw %bx > popw %ax > ret > >
