about framebuffer support in xen domain 0

about framebuffer support in xen domain 0

[qiang.wang]

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Hi, list,
I have a problem after moving the bootsplash patch into the domain 0
kernel. It doesn't work.
After digging the source code, I found that the kernel data "struct
screen_info screen_info" is set to a specific value in
arch/i386/kernel/setup-xen.c. And the info->video_type is
XEN_VGATYPE_TEXT_MODE_3, so it doesn't support framebuffer in domain 0
and the bootsplash either.

void __init setup_arch(char **cmdline_p)
{
...

if (is_initial_xendomain()) {
                /* This is drawn from a dump from vgacon:startup in
                 * standard Linux. */
                screen_info.orig_video_mode = 3;
                screen_info.orig_video_isVGA = 1;
                screen_info.orig_video_lines = 25;
                screen_info.orig_video_cols = 80;
                screen_info.orig_video_ega_bx = 3;
                screen_info.orig_video_points = 16;
                screen_info.orig_y = screen_info.orig_video_lines - 1;
                if (xen_start_info->console.dom0.info_size >=
                    sizeof(struct dom0_vga_console_info)) {
                        //const struct dom0_vga_console_info *info =
                        struct dom0_vga_console_info *info =
                                (struct dom0_vga_console_info *)(
                                        (char *)xen_start_info +
                                        xen_start_info-
>console.dom0.info_off);
                        // wangqiang
                        //info->video_type = XEN_VGATYPE_VESA_LFB;
                        dom0_init_screen_info(info);
                }
                xen_start_info->console.domU.mfn = 0;
                xen_start_info->console.domU.evtchn = 0;
        } else
                screen_info.orig_video_isVGA = 0;
...
}


it seems that the initial dom0_vga_console_info is set by
fill_console_start_info() in xen/drivers/video/vga.c
My question is that is there a particular reason to assign the
dom0_vga_console_info a specific value?

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Re: about framebuffer support in xen domain 0

[Keir Fraser]

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On 8/3/07 08:09, "qiang.wang" <qiang.wang@cs2c.com.cn> wrote:

> it seems that the initial dom0_vga_console_info is set by
> fill_console_start_info() in xen/drivers/video/vga.c
> My question is that is there a particular reason to assign the
> dom0_vga_console_info a specific value?

Yeah, you¹re pretty much stuck in the mode that Xen sets up for you, at
least for now. All the early video setup code needs to run in real mode.

 -- Keir


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