Re: kexec and framebuffer

From: Gerd Hoffmann
Date: Mon Jul 17 2006 - 10:27:43 EST


Hi,

> I am wondering what would be the preferred method to extract screen_info
> from running kernel. Should this be made available from sysfs or maybe a
> new system call be created?

Simply ask /dev/fb0?
Patch for kexec tools attached.

cheers,

Gerd

--
Gerd Hoffmann <kraxel@xxxxxxx>
http://www.suse.de/~kraxel/julika-dora.jpeg
Index: kexec-tools-1.101/kexec/arch/i386/x86-linux-setup.c
===================================================================
--- kexec-tools-1.101.orig/kexec/arch/i386/x86-linux-setup.c 2006-03-03 10:51:31.000000000 +0100
+++ kexec-tools-1.101/kexec/arch/i386/x86-linux-setup.c 2006-03-10 14:02:20.000000000 +0100
@@ -24,6 +24,8 @@
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/fb.h>
#include <unistd.h>
#include <x86/x86-linux.h>
#include "../../kexec.h"
@@ -94,6 +96,56 @@ void setup_linux_bootloader_parameters(
cmdline_ptr[cmdline_len - 1] = '\0';
}

+int setup_linux_vesafb(struct x86_linux_param_header *real_mode)
+{
+ struct fb_fix_screeninfo fix;
+ struct fb_var_screeninfo var;
+ int fd;
+
+ fd = open("/dev/fb0", O_RDONLY);
+ if (-1 == fd)
+ return -1;
+
+ if (-1 == ioctl(fd, FBIOGET_FSCREENINFO, &fix))
+ goto out;
+ if (-1 == ioctl(fd, FBIOGET_VSCREENINFO, &var))
+ goto out;
+ if (0 != strcmp(fix.id, "vesafb"))
+ goto out;
+ close(fd);
+
+ real_mode->orig_video_isVGA = 0x23 /* VIDEO_TYPE_VLFB */;
+ real_mode->lfb_width = var.xres;
+ real_mode->lfb_height = var.yres;
+ real_mode->lfb_depth = var.bits_per_pixel;
+ real_mode->lfb_base = fix.smem_start;
+ real_mode->lfb_linelength = fix.line_length;
+ real_mode->vesapm_seg = 0;
+
+ /* fixme: better get size from /proc/iomem */
+ real_mode->lfb_size = (fix.smem_len + 65535) / 65536;
+ real_mode->pages = (fix.smem_len + 4095) / 4096;
+
+ if (var.bits_per_pixel > 8) {
+ real_mode->red_pos = var.red.offset;
+ real_mode->red_size = var.red.length;
+ real_mode->green_pos = var.green.offset;
+ real_mode->green_size = var.green.length;
+ real_mode->blue_pos = var.blue.offset;
+ real_mode->blue_size = var.blue.length;
+ real_mode->rsvd_pos = var.transp.offset;
+ real_mode->rsvd_size = var.transp.length;
+ }
+ fprintf(stderr, "%s: %dx%dx%d @ %lx +%lx\n", __FUNCTION__,
+ var.xres, var.yres, var.bits_per_pixel,
+ fix.smem_start, fix.smem_len);
+ return 0;
+
+ out:
+ close(fd);
+ return -1;
+}
+
void setup_linux_system_parameters(struct x86_linux_param_header *real_mode,
unsigned long kexec_flags)
{
@@ -111,6 +163,7 @@ void setup_linux_system_parameters(struc
real_mode->orig_video_ega_bx = 0;
real_mode->orig_video_isVGA = 1;
real_mode->orig_video_points = 16;
+ setup_linux_vesafb(real_mode);

/* Fill in the memsize later */
real_mode->ext_mem_k = 0;