shithub: riscv

Download patch

ref: ca5cc6519de2b515e64775de4126dae29b3a1bde
parent: 858d3e39ab7e792c1d6e853ed699aeb5faf7d47c
author: mischief <[email protected]>
date: Sun Jun 8 20:22:11 EDT 2014

pc: clip rectangles before sending them to the hardware in flushmemscreen

the vmware svga video card emulated by qemu (qemu -vga vmware) complains and eventually causes a panic if the rectangles aren't clipped.

messages like the following can be observed from qemu before the kernel panics:
vmsvga_update_rect: update h was < 0 (-20000)
vmsvga_update_rect: update height too large y: 10000, h: 0
vmsvga_update_rect: update w was < 0 (-20000)
vmsvga_update_rect: update width too large x: 10000, w: 0

i could only reproduce this in qemu 2.0.50 on the master branch, when using the ui and had selected 'Zoom To Fit' from the View menu.

--- a/sys/src/9/pc/screen.c

+++ b/sys/src/9/pc/screen.c

@@ -179,12 +179,12 @@

 	scr = &vgascreen[0];

 	if(scr->gscreen == nil || scr->useflush == 0)

 		return;

+	if(rectclip(&r, scr->gscreen->r) == 0)

+		return;

 	if(scr->dev && scr->dev->flush){

 		scr->dev->flush(scr, r);

 		return;

 	}

-	if(rectclip(&r, scr->gscreen->r) == 0)

-		return;

 	disp = scr->vaddr;

 	incs = scr->gscreen->width*sizeof(ulong);

 	off = (r.min.x*scr->gscreen->depth) / 8;