x86, boot: make kernel_alignment adjustable; new bzImage fields
Make the kernel_alignment field adjustable; this allows us to set it
to a large value (intended to be 16 MB to avoid ZONE_DMA contention,
memory holes and other weirdness) while a smart bootloader can still
force a loading at a lesser alignment if absolutely necessary.
Also export pref_address (preferred loading address, corresponding to
the link-time address) and init_size, the total amount of linear
memory the kernel will require during initialization.
[ Impact: allows better kernel placement, gives bootloader more info ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 2728514..a0b4269 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -116,7 +116,7 @@
# Part 2 of the header, from the old setup.S
.ascii "HdrS" # header signature
- .word 0x0209 # header version number (>= 0x0105)
+ .word 0x020a # header version number (>= 0x0105)
# or else old loadlin-1.5 will fail)
.globl realmode_swtch
realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
@@ -201,7 +201,7 @@
#else
relocatable_kernel: .byte 0
#endif
-pad2: .byte 0
+min_alignment: .byte MIN_KERNEL_ALIGN_LG2 # minimum alignment
pad3: .word 0
cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
@@ -220,6 +220,17 @@
# single linked list of
# struct setup_data
+pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr
+
+#define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_extract_offset)
+#define VO_INIT_SIZE (VO__end - VO__text)
+#if ZO_INIT_SIZE > VO_INIT_SIZE
+#define INIT_SIZE ZO_INIT_SIZE
+#else
+#define INIT_SIZE VO_INIT_SIZE
+#endif
+init_size: .long INIT_SIZE # kernel initialization size
+
# End of setup header #####################################################
.section ".inittext", "ax"