um: Remove file-based iomem emulation support

The file-based iomem emulation was introduced to support writing
paravirtualized drivers based on emulated iomem regions. However,
the only driver that makes use of it is an example driver called
mmapper, which was written over two decades ago.

We now have several modern device emulation mechanisms, such as
vhost-user-based virtio-uml. Remove the file-based iomem emulation
support to reduce the maintenance burden.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20251027054519.1996090-5-tiwei.bie@linux.dev
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 0 insertions, 71 deletions

diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
index af02b5f9911d..ae6ca373c261 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -105,19 +105,6 @@ int phys_mapping(unsigned long phys, unsigned long long *offset_out)
 		fd = physmem_fd;
 		*offset_out = phys;
 	}
-	else if (phys < __pa(end_iomem)) {
-		struct iomem_region *region = iomem_regions;
-
-		while (region != NULL) {
-			if ((phys >= region->phys) &&
-			    (phys < region->phys + region->size)) {
-				fd = region->fd;
-				*offset_out = phys - region->phys;
-				break;
-			}
-			region = region->next;
-		}
-	}
 
 	return fd;
 }
@@ -140,61 +127,3 @@ __uml_setup("mem=", uml_mem_setup,
 "    be more, and the excess, if it's ever used, will just be swapped out.\n"
 "	Example: mem=64M\n\n"
 );
-
-__uml_setup("iomem=", parse_iomem,
-"iomem=<name>,<file>\n"
-"    Configure <file> as an IO memory region named <name>.\n\n"
-);
-
-/*
- * This list is constructed in parse_iomem and addresses filled in
- * setup_iomem, both of which run during early boot.  Afterwards, it's
- * unchanged.
- */
-struct iomem_region *iomem_regions;
-
-/* Initialized in parse_iomem and unchanged thereafter */
-int iomem_size;
-
-unsigned long find_iomem(char *driver, unsigned long *len_out)
-{
-	struct iomem_region *region = iomem_regions;
-
-	while (region != NULL) {
-		if (!strcmp(region->driver, driver)) {
-			*len_out = region->size;
-			return region->virt;
-		}
-
-		region = region->next;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL(find_iomem);
-
-static int setup_iomem(void)
-{
-	struct iomem_region *region = iomem_regions;
-	unsigned long iomem_start = high_physmem + PAGE_SIZE;
-	int err;
-
-	while (region != NULL) {
-		err = os_map_memory((void *) iomem_start, region->fd, 0,
-				    region->size, 1, 1, 0);
-		if (err)
-			printk(KERN_ERR "Mapping iomem region for driver '%s' "
-			       "failed, errno = %d\n", region->driver, -err);
-		else {
-			region->virt = iomem_start;
-			region->phys = __pa(region->virt);
-		}
-
-		iomem_start += region->size + PAGE_SIZE;
-		region = region->next;
-	}
-
-	return 0;
-}
-
-__initcall(setup_iomem);