Ok, here we go:

Make fb layer aware of the difference between the ioremap()'ed VRAM and
total available VRAM.
smem_len in struct fb_fix_screeninfo contains the amount of physical
VRAM (reported to userspace via FBIOGET_FSCREENINFO ioctl) while the new
field mapped_vram in struct fb_info contains the amount of VRAM actually
ioremap()'ed by drivers (used in read/write/mmap operations).
If mapped_vram is not set it's assumed that the entire framebuffer is
mapped, thus other drivers are unaffected by this patch.

Signed-off-by: Luca Tettamanti <redacted>

--- a/include/linux/fb.h	2004-11-30 18:30:08.000000000 +0100
+++ b/include/linux/fb.h	2004-12-02 14:20:50.000000000 +0100

@@ -323,6 +323,7 @@
    struct fb_cmap cmap;                 /* Current cmap */
    struct fb_ops *fbops;
    char *screen_base;                   /* Virtual address */
+   u32 mapped_vram;			/* ioremap()'ed VRAM */
    struct display *disp;		/* initial display variable */
    struct vc_data *display_fg;		/* Console visible on this display */
    char fontname[40];			/* default font name */
--- a/drivers/video/fbmem.c	2004-11-30 18:30:00.000000000 +0100
+++ b/drivers/video/fbmem.c	2004-12-02 14:29:44.000000000 +0100

@@ -410,6 +410,7 @@
 	struct fb_info *info = registered_fb[fbidx];
 	struct fb_ops *fb = info->fbops;
 	struct fb_fix_screeninfo fix;
+	unsigned int size;
 
 	if (! fb || ! info->disp)
 		return -ENODEV;

@@ -418,10 +419,12 @@
 		return -EINVAL;
 
 	fb->fb_get_fix(&fix,PROC_CONSOLE(info), info);
-	if (p >= fix.smem_len)
+	size = info->mapped_vram ? info->mapped_vram : fix.smem_len;
+	
+	if (p >= size)
 	    return 0;
-	if (count > fix.smem_len - p)
-		count = fix.smem_len - p;
+	if (count > size - p)
+		count = size - p;
 	if (count) {
 	    char *base_addr;
 

@@ -444,6 +447,7 @@
 	struct fb_ops *fb = info->fbops;
 	struct fb_fix_screeninfo fix;
 	int err;
+	unsigned int size;
 
 	if (! fb || ! info->disp)
 		return -ENODEV;

@@ -452,11 +456,13 @@
 		return -EINVAL;
 
 	fb->fb_get_fix(&fix, PROC_CONSOLE(info), info);
-	if (p > fix.smem_len)
+	size = info->mapped_vram ? info->mapped_vram : fix.smem_len;
+	
+	if (p > size)
 	    return -ENOSPC;
 	err = 0;
-	if (count > fix.smem_len - p) {
-	    count = fix.smem_len - p;
+	if (count > size - p) {
+	    count = size - p;
 	    err = -ENOSPC;
 	}
 	if (count) {

@@ -619,7 +625,10 @@
 
 	/* frame buffer memory */
 	start = fix.smem_start;
-	len = PAGE_ALIGN((start & ~PAGE_MASK)+fix.smem_len);
+	if (info->mapped_vram)
+		len = PAGE_ALIGN((start & ~PAGE_MASK) + info->mapped_vram);
+	else
+		len = PAGE_ALIGN((start & ~PAGE_MASK) + fix.smem_len);
 	if (off >= len) {
 		/* memory mapped io */
 		off -= len;
--- a/drivers/video/radeonfb.c	2004-11-30 18:06:45.000000000 +0100
+++ b/drivers/video/radeonfb.c	2004-12-02 14:28:10.000000000 +0100

@@ -176,7 +176,8 @@
 #define RTRACE		if(0) printk
 #endif
 
-
+#define MAX_MAPPED_VRAM (2048*2048*4)
+#define MIN_MAPPED_VRAM (1024*768*1)
 
 enum radeon_chips {
 	RADEON_QD,

@@ -499,7 +500,7 @@
 
 	short chipset;
 	unsigned char arch;
-	int video_ram;
+	unsigned int video_ram;
 	u8 rev;
 	int pitch, bpp, depth;
 	int xres, yres, pixclock;

@@ -1626,6 +1627,7 @@
 				  const struct pci_device_id *ent)
 {
 	struct radeonfb_info *rinfo;
+	struct fb_info *fb_info;
 	struct radeon_chip_info *rci = &radeon_chip_info[ent->driver_data];
 	u32 tmp;
 	int i, j;

@@ -1640,6 +1642,7 @@
 
 	memset (rinfo, 0, sizeof (struct radeonfb_info));
 
+	fb_info = (struct fb_info *)rinfo;
 	rinfo->pdev = pdev;
 	strncpy(rinfo->name, rci->name, 16);
 	rinfo->arch = rci->arch;

@@ -1824,8 +1827,16 @@
 		}
 	}
 
-	rinfo->fb_base = (unsigned long) ioremap (rinfo->fb_base_phys,
-				  		  rinfo->video_ram);
+	fb_info->mapped_vram = min_t(unsigned int, MAX_MAPPED_VRAM, rinfo->video_ram);
+	do {
+		rinfo->fb_base = (unsigned long) ioremap (rinfo->fb_base_phys,
+				  		  fb_info->mapped_vram);
+		if (rinfo->fb_base)
+			break;
+
+		fb_info->mapped_vram /= 2;
+	} while(fb_info->mapped_vram > MIN_MAPPED_VRAM);
+	
 	if (!rinfo->fb_base) {
 		printk ("radeonfb: cannot map FB\n");
 		iounmap ((void*)rinfo->mmio_base);

@@ -1836,6 +1847,7 @@
 		kfree (rinfo);
 		return -ENODEV;
 	}
+	RTRACE(KERN_INFO "radeonfb: mapped %dk videoram\n", fb_info->mapped_vram/1024);
 
 	/* currcon not yet configured, will be set by first switch */
 	rinfo->currcon = -1;

@@ -2199,13 +2211,14 @@
                 {-1, -1}
         };
         int i;
+	struct fb_info *fb_info = (struct fb_info *)rinfo;
                 
         /* use highest possible virtual resolution */
         if (v->xres_virtual == -1 && v->yres_virtual == -1) {
                 printk("radeonfb: using max available virtual resolution\n");
                 for (i=0; modes[i].xres != -1; i++) {
                         if (modes[i].xres * nom / den * modes[i].yres <
-                            rinfo->video_ram / 2)
+                            fb_info->mapped_vram / 2)
                                 break;
                 }
                 if (modes[i].xres == -1) {

@@ -2218,15 +2231,15 @@
                 printk("radeonfb: virtual resolution set to max of %dx%d\n",
                         v->xres_virtual, v->yres_virtual);
         } else if (v->xres_virtual == -1) {
-                v->xres_virtual = (rinfo->video_ram * den /   
+                v->xres_virtual = (fb_info->mapped_vram * den /   
                                 (nom * v->yres_virtual * 2)) & ~15;
         } else if (v->yres_virtual == -1) {
                 v->xres_virtual = (v->xres_virtual + 15) & ~15;
-                v->yres_virtual = rinfo->video_ram * den /
+                v->yres_virtual = fb_info->mapped_vram * den /
                         (nom * v->xres_virtual *2);
         } else {
                 if (v->xres_virtual * nom / den * v->yres_virtual >
-                        rinfo->video_ram) {
+                        fb_info->mapped_vram) {
                         return -EINVAL;
                 }
         }

@@ -2430,6 +2443,9 @@
                         return -EINVAL;
         }
 
+	if (((v.xres_virtual * v.yres_virtual * nom) / den) > info->mapped_vram)
+		return -EINVAL;
+
         if (radeonfb_do_maximize(rinfo, var, &v, nom, den) < 0)
                 return -EINVAL;  
                 

Luca
-- 
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