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, 50 deletions

diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index a827c2e01aa5..8b19dca83f71 100644
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -489,53 +489,3 @@ void __init os_early_checks(void)
 		fatal("Failed to initialize default registers");
 	stop_ptraced_child(pid, 1);
 }
-
-int __init parse_iomem(char *str, int *add)
-{
-	struct iomem_region *new;
-	struct stat64 buf;
-	char *file, *driver;
-	int fd, size;
-
-	driver = str;
-	file = strchr(str,',');
-	if (file == NULL) {
-		os_warn("parse_iomem : failed to parse iomem\n");
-		goto out;
-	}
-	*file = '\0';
-	file++;
-	fd = open(file, O_RDWR, 0);
-	if (fd < 0) {
-		perror("parse_iomem - Couldn't open io file");
-		goto out;
-	}
-
-	if (fstat64(fd, &buf) < 0) {
-		perror("parse_iomem - cannot stat_fd file");
-		goto out_close;
-	}
-
-	new = malloc(sizeof(*new));
-	if (new == NULL) {
-		perror("Couldn't allocate iomem_region struct");
-		goto out_close;
-	}
-
-	size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
-
-	*new = ((struct iomem_region) { .next		= iomem_regions,
-					.driver		= driver,
-					.fd		= fd,
-					.size		= size,
-					.phys		= 0,
-					.virt		= 0 });
-	iomem_regions = new;
-	iomem_size += new->size + UM_KERN_PAGE_SIZE;
-
-	return 0;
- out_close:
-	close(fd);
- out:
-	return 1;
-}