[SeaBIOS] [PATCH 08/15] Fix finding VESA mode

[Christian Gmeiner]

2012/9/3 Kevin O'Connor <kevin at koconnor.net>:
> On Mon, Sep 03, 2012 at 06:12:34PM +0200, Christian Gmeiner wrote:
>> 2012/9/3 Kevin O'Connor <kevin at koconnor.net>:
>> > On Sat, Sep 01, 2012 at 05:12:59PM +0200, Christian Gmeiner wrote:
>> >> With the current code the following happens:
>> >>
>> >> VBE mode info request: 4101
>> >> VBE mode 4101 not found
>> >> get_mode failed.
>> >>
>> >> Looking at the provided mode (cx register) only bits 8-0
>> >> define the video mode number. I am not sure if the current
>> >> code ever worked.
>> >>
>> >> Signed-off-by: Christian Gmeiner <christian.gmeiner at gmail.com>
>> >> ---
>> >>  vgasrc/vbe.c | 17 ++++++++++++++++-
>> >>  1 file changed, 16 insertions(+), 1 deletion(-)
>> >>
>> >> diff --git a/vgasrc/vbe.c b/vgasrc/vbe.c
>> >> index 227a244..af72324 100644
>> >> --- a/vgasrc/vbe.c
>> >> +++ b/vgasrc/vbe.c
>> >> @@ -72,9 +72,24 @@ vbe_104f01(struct bregs *regs)
>> >>      struct vbe_mode_info *info = (void*)(regs->di+0);
>> >>      u16 mode = regs->cx;
>> >>
>> >> +    /*
>> >> +     * Bitfields for VESA/VBE video mode number:
>> >> +     *
>> >> +     * Bit(s)  Description     (Table 04082)
>> >> +     * 15     preserve display memory on mode change
>> >> +     * 14     (VBE v2.0+) use linear (flat) frame buffer
>> >> +     * 13     (VBE/AF 1.0P) VBE/AF initializes accelerator hardware
>> >> +     * 12     reserved for VBE/AF
>> >> +     * 11     (VBE v3.0) user user-specified CRTC refresh rate values
>> >> +     * 10-9   reserved for future expansion
>> >> +     * 8-0    video mode number (0xxh are non-VESA modes, 1xxh are VESA-defined)
>> >> +     *
>> >> +     * see http://www.ctyme.com/intr/rb-0274.htm
>> >> +     */
>> >
>> > This is true for the call to set mode (vbe_104f02), but the spec does
>> > not say this for the get mode info call (104f01).  It would be odd to
>> > pass in these additional bits when the caller just wants to get info
>> > on the given mode.
>>
>> But if I want more information's about mode 0x101 with linear
>> framebuffer support - thats
>> the only way to get it. Also this is triggered by src/bootsplash.c so
>> it seems to be a valid
>> use-case.
>
> Okay - looking at this closer.  It looks to me that what bootsplash is
> doing is wrong.  However, it also looks like real vgabios will ignore
> the bits.  So, I propose changing both bootsplash and the vbe code.
>
> Thanks.
>
> -Kevin
>
>
> From c8a3d3ee0194f0bb76e7ec8eeb59d7b986c24016 Mon Sep 17 00:00:00 2001
> From: Kevin O'Connor <kevin at koconnor.net>
> Date: Mon, 3 Sep 2012 13:52:50 -0400
> Subject: [PATCH 1/2] bootsplash: Don't pass mode flags to VBE get_mode_info
>  call.
> To: seabios at seabios.org
>
> The spec doesn't specify one can pass flags into the get_mode_info
> call, so don't do that.
>
> Also, use the VBE_MODE_LINEAR_FRAME_BUFFER name where appropriate.
>
> Signed-off-by: Kevin O'Connor <kevin at koconnor.net>
> ---
>  src/bootsplash.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/src/bootsplash.c b/src/bootsplash.c
> index a85e2b2..78023a5 100644
> --- a/src/bootsplash.c
> +++ b/src/bootsplash.c
> @@ -11,7 +11,8 @@
>  #include "util.h" // dprintf
>  #include "jpeg.h" // splash
>  #include "vbe.h" // struct vbe_info
> -#include "bmp.h"
> +#include "bmp.h" // bmp_alloc
> +
>
>  /****************************************************************
>   * Helper functions
> @@ -63,7 +64,7 @@ find_videomode(struct vbe_info *vesa_info, struct vbe_mode_info *mode_info
>          struct bregs br;
>          memset(&br, 0, sizeof(br));
>          br.ax = 0x4f01;
> -        br.cx = (1 << 14) | videomode;
> +        br.cx = videomode;
>          br.di = FLATPTR_TO_OFFSET(mode_info);
>          br.es = FLATPTR_TO_SEG(mode_info);
>          call16_int10(&br);
> @@ -216,7 +217,7 @@ enable_bootsplash(void)
>      dprintf(5, "Switching to graphics mode\n");
>      memset(&br, 0, sizeof(br));
>      br.ax = 0x4f02;
> -    br.bx = (1 << 14) | videomode;
> +    br.bx = videomode | VBE_MODE_LINEAR_FRAME_BUFFER;
>      call16_int10(&br);
>      if (br.ax != 0x4f) {
>          dprintf(1, "set_mode failed.\n");
> --
> 1.7.11.4
>
>
>
> From ef4f9e183751df5ccd32eb5dda2ce6816b53695f Mon Sep 17 00:00:00 2001
> From: Kevin O'Connor <kevin at koconnor.net>
> Date: Mon, 3 Sep 2012 13:54:28 -0400
> Subject: [PATCH 2/2] vgabios: Ignore mode flags in vbe get_mode_info call.
> To: seabios at seabios.org
>
> Ignore any mode flags a caller may have set on the vbe get_mode_info
> call.  The spec doesn't require ignoring of flags, but it appears at
> least some real-world vgabios vbe implementations do this.
>
> Signed-off-by: Kevin O'Connor <kevin at koconnor.net>
> ---
>  vgasrc/vbe.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/vgasrc/vbe.c b/vgasrc/vbe.c
> index 227a244..01c8071 100644
> --- a/vgasrc/vbe.c
> +++ b/vgasrc/vbe.c
> @@ -74,7 +74,7 @@ vbe_104f01(struct bregs *regs)
>
>      dprintf(1, "VBE mode info request: %x\n", mode);
>
> -    struct vgamode_s *vmode_g = vgahw_find_mode(mode);
> +    struct vgamode_s *vmode_g = vgahw_find_mode(mode & ~MF_VBEFLAGS);
>      if (! vmode_g) {
>          dprintf(1, "VBE mode %x not found\n", mode);
>          regs->ax = 0x014f;
> --
> 1.7.11.4
>

Both patches are fine...

Acked-by: Christian Gmeiner <christian.gmeiner at gmail.com>
---
Christian Gmeiner, MSc