[SeaBIOS] [PATCH 3/6] qemu: add bochs-display support

[Kevin O'Connor]

On Thu, May 31, 2018 at 08:33:50AM +0200, Gerd Hoffmann wrote:
[...]
> +     dprintf(1, "bochs-display: using %dx%d, %d bpp (%d stride)\n"
> +            , FRAMEBUFFER_WIDTH, FRAMEBUFFER_HEIGHT
> +            , FRAMEBUFFER_BPP * 8, FRAMEBUFFER_STRIDE);
> +
> +    cbvga_setup_modes(lfb_addr, FRAMEBUFFER_BPP * 8,
> +                      FRAMEBUFFER_WIDTH, FRAMEBUFFER_HEIGHT,
> +                      FRAMEBUFFER_STRIDE);
> +
> +    writew(dispi + VBE_DISPI_INDEX_XRES,   FRAMEBUFFER_WIDTH);
> +    writew(dispi + VBE_DISPI_INDEX_YRES,   FRAMEBUFFER_HEIGHT);
> +    writew(dispi + VBE_DISPI_INDEX_BPP,    FRAMEBUFFER_BPP * 8);
> +    writew(dispi + VBE_DISPI_INDEX_ENABLE, VBE_DISPI_ENABLED);
> +
> +    writeb(vga, 0x20); /* unblank (for qemu -device VGA) */

An additional question - if the mode can be changed why do we only
change it on startup?  Is the idea that the OS will have a driver
installed that directly changes modes once the OS starts up?

-Kevin