Linux开机液晶屏Logo显示：boot-logo bigger than screen

前不久，因为工作需要更换了液晶屏，分辨率由原来的800*480换成了800*600。

当然首先更改了液晶屏驱动，修改了相应的参数。把开机Logo也进行了更换，分辨率修改为800*600。

但是开机时，Logo无法显示，提示以下错误。

fbcon_init: disable boot-logo (boot-logo bigger than screen).

真是扯淡啊，查看源代码，该提示在drvers/video/console/Fbcon.c下，在此截取这段代码。

static void fbcon_prepare_logo(struct vc_data *vc, struct fb_info *info,       int cols, int rows, int new_cols, int new_rows){/* Need to make room for the logo */struct fbcon_ops *ops = info->fbcon_par;int cnt, erase = vc->vc_video_erase_char, step;unsigned short *save = NULL, *r, *q;int logo_height;if (info->flags & FBINFO_MODULE) {logo_shown = FBCON_LOGO_DONTSHOW;return;}/* * remove underline attribute from erase character * if black and white framebuffer. */if (fb_get_color_depth(&info->var, &info->fix) == 1)erase &= ~0x400;logo_height = fb_prepare_logo(info, ops->rotate);        //logo_lines在此赋值logo_lines = DIV_ROUND_UP(logo_height, vc->vc_font.height);q = (unsigned short *) (vc->vc_origin +vc->vc_size_row * rows);step = logo_lines * cols;for (r = q - logo_lines * cols; r < q; r++)if (scr_readw(r) != vc->vc_video_erase_char)break;if (r != q && new_rows >= rows + logo_lines) {save = kmalloc(logo_lines * new_cols * 2, GFP_KERNEL);if (save) {int i = cols < new_cols ? cols : new_cols;scr_memsetw(save, erase, logo_lines * new_cols * 2);r = q - step;for (cnt = 0; cnt < logo_lines; cnt++, r += i)scr_memcpyw(save + cnt * new_cols, r, 2 * i);r = q;}}if (r == q) {/* We can scroll screen down */r = q - step - cols;for (cnt = rows - logo_lines; cnt > 0; cnt--) {scr_memcpyw(r + step, r, vc->vc_size_row);r -= cols;}if (!save) {int lines;if (vc->vc_y + logo_lines >= rows)lines = rows - vc->vc_y - 1;elselines = logo_lines;vc->vc_y += lines;vc->vc_pos += lines * vc->vc_size_row;}}scr_memsetw((unsigned short *) vc->vc_origin,    erase,    vc->vc_size_row * logo_lines);if (CON_IS_VISIBLE(vc) && vc->vc_mode == KD_TEXT) {fbcon_clear_margins(vc, 0);update_screen(vc);}if (save) {q = (unsigned short *) (vc->vc_origin +vc->vc_size_row *rows);scr_memcpyw(q, save, logo_lines * new_cols * 2);vc->vc_y += logo_lines;vc->vc_pos += logo_lines * vc->vc_size_row;kfree(save);}//错误提示在此if (logo_lines > vc->vc_bottom) {logo_shown = FBCON_LOGO_CANSHOW;printk(KERN_INFO       "fbcon_init: disable boot-logo (boot-logo bigger than screen).\n");} else if (logo_shown != FBCON_LOGO_DONTSHOW) {logo_shown = FBCON_LOGO_DRAW;vc->vc_top = logo_lines;}}

可以发现是因为logo_lines > vc->vc_bottom引起的。

其中logo_lines = DIV_ROUND_UP(logo_height, vc->vc_font.height);    //（DIV_ROUND_UP是向上取整的意思）

而vc->vc_bottom代码读下来为vc->vc_bottom  = info->var.yres/ vc->vc_font.height;

其关键就是vc->vc_font.height了，Linux下vc->vc_font.height默认为16，所以当液晶屏和Logo的分辨率都为800*600时，600/16无法整除，故取整logo_lines =38;  vc->vc_bottom = 37;提示错误无法显示。

只要把logo的改小一下，改为592，则logo_lines = 592/16=37；  vc->vc_bottom = 600/16=37；就可以正常显示了。

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