[Xen-devel] [PATCH v2 5/8] xen/x86: add some addresses to the Multiboot2 header

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

In comparison to ELF the PE format is not supported by the Multiboot2
protocol. So, if we wish to load xen.mb.efi using this protocol we have
to add MULTIBOOT2_HEADER_TAG_ADDRESS and MULTIBOOT2_HEADER_TAG_ENTRY_ADDRESS
tags into Multiboot2 header.

Additionally, put MULTIBOOT2_HEADER_TAG_ENTRY_ADDRESS and
MULTIBOOT2_HEADER_TAG_ENTRY_ADDRESS_EFI64 tags close to each
other to make the header more readable.

The Multiboot2 protocol spec can be found at
  https://www.gnu.org/software/grub/manual/multiboot2/

Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
---
v2 - suggestions/fixes:
   - add the pointer to the Multiboot2 protocol spec to the commit message
     (suggested by Konrad Rzeszutek Wilk),
   - improve commit message
     (suggested by Konrad Rzeszutek Wilk).
---
 xen/arch/x86/boot/head.S |   19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 3ed43d9..582dc51 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -245,6 +245,13 @@ multiboot2_header:
         /* Align modules at page boundry. */
         mb2ht_init MB2_HT(MODULE_ALIGN), MB2_HT(REQUIRED)
 
+        /* The address tag. */
+        mb2ht_init MB2_HT(ADDRESS), MB2_HT(REQUIRED), \
+                   sym_offs(multiboot2_header), /* header_addr */ \
+                   sym_offs(start),             /* load_addr */ \
+                   sym_offs(__bss_start),       /* load_end_addr */ \
+                   sym_offs(__2M_rwdata_end)    /* bss_end_addr */
+
         /* Load address preference. */
         mb2ht_init MB2_HT(RELOCATABLE), MB2_HT(OPTIONAL), \
                    sym_offs(start), /* Min load address. */ \
@@ -252,6 +259,14 @@ multiboot2_header:
                    0x200000, /* Load address alignment (2 MiB). */ \
                    MULTIBOOT2_LOAD_PREFERENCE_HIGH
 
+        /* Multiboot2 entry point. */
+        mb2ht_init MB2_HT(ENTRY_ADDRESS), MB2_HT(REQUIRED), \
+                   sym_offs(__start)
+
+        /* EFI64 Multiboot2 entry point. */
+        mb2ht_init MB2_HT(ENTRY_ADDRESS_EFI64), MB2_HT(OPTIONAL), \
+                   sym_offs(__efi64_mb2_start)
+
         /* Console flags tag. */
         mb2ht_init MB2_HT(CONSOLE_FLAGS), MB2_HT(OPTIONAL), \
                    MULTIBOOT2_CONSOLE_FLAGS_EGA_TEXT_SUPPORTED
@@ -265,10 +280,6 @@ multiboot2_header:
         /* Request that ExitBootServices() not be called. */
         mb2ht_init MB2_HT(EFI_BS), MB2_HT(OPTIONAL)
 
-        /* EFI64 Multiboot2 entry point. */
-        mb2ht_init MB2_HT(ENTRY_ADDRESS_EFI64), MB2_HT(OPTIONAL), \
-                   sym_offs(__efi64_mb2_start)
-
         /* Multiboot2 header end tag. */
         mb2ht_init MB2_HT(END), MB2_HT(REQUIRED)
 .Lmultiboot2_header_end:
-- 
1.7.10.4


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