[Qemu-devel] [PATCH] multiboot: mh_load_end_addr and mh_bss_end_addr may be zero

[Göran Weinholt]

There are two special cases in the address fields of the multiboot
format. If mh_load_end_addr is zero then the whole image file should
be loaded and if mh_bss_end_addr is zero then there is no bss segment.
With this change it is again possible to boot kernels where these
fields are zero.

Signed-off-by: Göran Weinholt <go...@weinholt.se>
Tested-by: Alexander Graf <ag...@suse.de>
---
 hw/multiboot.c |   15 ++++++++++++++-
 1 files changed, 14 insertions(+), 1 deletions(-)

diff --git a/hw/multiboot.c b/hw/multiboot.c
index b4484a3..db28328 100644
--- a/hw/multiboot.c
+++ b/hw/multiboot.c
@@ -202,10 +202,23 @@ int load_multiboot(void *fw_cfg,
         uint32_t mh_bss_end_addr = ldl_p(header+i+24);
         mh_load_addr = ldl_p(header+i+16);
         uint32_t mb_kernel_text_offset = i - (mh_header_addr - mh_load_addr);
-        uint32_t mb_load_size = mh_load_end_addr - mh_load_addr;
+        uint32_t mb_load_size;
+
+        /* A load end address of zero indicates that the whole file
+         * should be loaded. */
+        if (!mh_load_end_addr) {
+            mh_load_end_addr = kernel_file_size + mh_load_addr;
+        }
+
+        /* A bss end address of zero indicates that there is no bss
+         * segment. */
+        if (!mh_bss_end_addr) {
+            mh_bss_end_addr = mh_load_end_addr;
+        }
 
         mh_entry_addr = ldl_p(header+i+28);
         mb_kernel_size = mh_bss_end_addr - mh_load_addr;
+        mb_load_size = mh_load_end_addr - mh_load_addr;
 
         /* Valid if mh_flags sets MULTIBOOT_HEADER_HAS_VBE.
         uint32_t mh_mode_type = ldl_p(header+i+32);
-- 
1.7.2.5