--- include/video/impact.h	(revision 60)
+++ include/video/impact.h	(revision 61)
@@ -334,4 +334,11 @@
 #define impact_cmd_hq_484B(a, p, v)		ImpactCFifoPCmd64(a, (0x00484b04 + ((p) << 8)), 0, v)
 */
 
+struct impact_cf_args
+{
+	struct winsize box;		/* termios.h */
+	unsigned long long base;
+	unsigned bpitch;
+};
+
 #endif /* _IMPACT_H */

--- drivers/video/fbdev/impact.c	(revision 60)
+++ drivers/video/fbdev/impact.c	(revision 63)
@@ -81,6 +81,7 @@
  * @pool_txphys: txphys[p] = dma_addr(txtbl[p]).
  * @kpool_virt: virt[p]: txnum[p] page_addr.
  * @kpool_phys: phys[p][i] = dma_addr(virt[p][i]).
+ * @kpool_uaddr: kpool_uaddr[p] = DMA-buffer's userland-address
  * @kpool_size: TBD.
  * @num_rss: TBD.
  * @open_flag: TBD.
@@ -102,8 +103,9 @@
 	/* Kernel DMA pools. */
 	unsigned long **kpool_virt[MAX_POOLS];
 	unsigned long *kpool_phys[MAX_POOLS];
+	unsigned long kpool_uaddr[MAX_POOLS];
 	u32 kpool_size[MAX_POOLS];
-
+	
 	/* Board config. */
 	u32 num_ge;
 	u32 num_rss;
@@ -151,6 +153,7 @@
 
 /* ----------------------------------------------------------------------- */
 /* Gory details */
+#define PAR(p)  (*((struct impact_par *)(p)->par))
 #define MMIO (((struct impact_par *)info->par)->mmio_virt)
 
 /**
@@ -877,6 +880,30 @@
 /* ----------------------------------------------------------------------- */
 /* Userland access */
 
+static int
+impact_cacheflush(struct fb_info *info, int pool, const struct impact_cf_args *arg)
+{
+	struct impact_par *par = info->par;
+	unsigned short w = arg->box.ws_xpixel << 2;
+	unsigned short h = arg->box.ws_ypixel;
+
+	if (w && h)
+	{
+		unsigned long a = arg->bpitch*arg->box.ws_row + (arg->box.ws_col << 2);
+		unsigned long b = arg->base + par->kpool_size[pool] - w;
+
+		for (a += arg->base; h; h--, a += arg->bpitch)
+		{
+			if (!access_ok(VERIFY_WRITE, (void __user*)a, w))
+				return -EFAULT;
+			if (b <= a)
+				return -EINVAL;
+			dma_cache_wback_inv(a, w);
+		}
+	}
+	return 0;
+}
+
 /**
  * impact_fb_ioctl - framebuffer ioctl() access (unimplemented).
  * @info: struct fb_info pointer to framebuffer data.
@@ -886,6 +913,33 @@
 static int
 impact_fb_ioctl(struct fb_info *info, u32 cmd, unsigned long arg)
 {
+#ifdef SGI_INDIGO2
+	if (TCFLSH == cmd) {
+		struct impact_par *par = info->par;
+		static struct impact_cf_args cfpar;
+		int i;
+
+		if ( copy_from_user(&cfpar, (void __user*)arg, sizeof(cfpar)) )
+			return -EFAULT;
+
+		if (!cfpar.base)
+			return -EINVAL;
+
+		for (i = 0; i < MAX_POOLS; i++) {
+			if (cfpar.base == par->kpool_uaddr[i]) {
+				int r = impact_cacheflush(info, i, &cfpar);
+				/* Might be munmapped behind our back. */
+				if (-EFAULT == r) {
+					printk(KERN_INFO "impact_ioctl: shut down user"
+						" cache-flush for DMA-pool %d (%p)\n",
+						i, (void*)cfpar.base);
+					par->kpool_uaddr[i] = 0;
+				}
+				return r;
+			}
+		}
+	}
+#endif
 	return -EINVAL;
 }
 /* ----------------------------------------------------------------------- */
@@ -912,8 +966,11 @@
 
 	switch (offset) {
 	case 0x0000000:
-	default:
+#ifndef SGI_INDIGO2
 		if (unlikely((offset + size) > 0x200000))
+#else
+		if (unlikely((offset + size) > 0x400000))
+#endif
 			return -EINVAL;
 
 		if (unlikely(vma->vm_pgoff > (~0UL >> PAGE_SHIFT)))
@@ -947,10 +1004,16 @@
 			pfn = (par->kpool_phys[pool][i] >> PAGE_SHIFT);
 			ret = remap_pfn_range(vma, start, pfn, PAGE_SIZE,
 					      vma->vm_page_prot);
-			if (unlikely(ret))
+			if (unlikely(ret)) {
+				par->kpool_uaddr[pool] = 0;
 				return -EAGAIN;
+			}
 			start += PAGE_SIZE;
 		}
+		par->kpool_uaddr[pool] = vma->vm_start;
+		break;
+	default:
+		return -EINVAL;
 	}
 
 	return 0;