um: Print minimum physical memory requirement
Print a more sensible message about the minimum physical memory
requirement.
Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
index 549ecf3..9034fc8 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -57,22 +57,51 @@
extern int __syscall_stub_start;
+/**
+ * setup_physmem() - Setup physical memory for UML
+ * @start: Start address of the physical kernel memory,
+ * i.e start address of the executable image.
+ * @reserve_end: end address of the physical kernel memory.
+ * @len: Length of total physical memory that should be mapped/made
+ * available, in bytes.
+ * @highmem: Number of highmem bytes that should be mapped/made available.
+ *
+ * Creates an unlinked temporary file of size (len + highmem) and memory maps
+ * it on the last executable image address (uml_reserved).
+ *
+ * The offset is needed as the length of the total physical memory
+ * (len + highmem) includes the size of the memory used be the executable image,
+ * but the mapped-to address is the last address of the executable image
+ * (uml_reserved == end address of executable image).
+ *
+ * The memory mapped memory of the temporary file is used as backing memory
+ * of all user space processes/kernel tasks.
+ */
void __init setup_physmem(unsigned long start, unsigned long reserve_end,
unsigned long len, unsigned long long highmem)
{
unsigned long reserve = reserve_end - start;
- int pfn = PFN_UP(__pa(reserve_end));
- int delta = (len - reserve) >> PAGE_SHIFT;
- int err, offset, bootmap_size;
+ unsigned long pfn = PFN_UP(__pa(reserve_end));
+ unsigned long delta = (len - reserve) >> PAGE_SHIFT;
+ unsigned long offset, bootmap_size;
+ long map_size;
+ int err;
+
+ offset = uml_reserved - uml_physmem;
+ map_size = len - offset;
+ if(map_size <= 0) {
+ printf("Too few physical memory! Needed=%d, given=%d\n",
+ offset, len);
+ exit(1);
+ }
physmem_fd = create_mem_file(len + highmem);
- offset = uml_reserved - uml_physmem;
err = os_map_memory((void *) uml_reserved, physmem_fd, offset,
- len - offset, 1, 1, 1);
+ map_size, 1, 1, 1);
if (err < 0) {
printf("setup_physmem - mapping %ld bytes of memory at 0x%p "
- "failed - errno = %d\n", len - offset,
+ "failed - errno = %d\n", map_size,
(void *) uml_reserved, err);
exit(1);
}