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>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c
index e72f062fb4b..898ecc47e12 100644
--- a/arch/x86/kernel/asm-offsets_64.c
+++ b/arch/x86/kernel/asm-offsets_64.c
@@ -125,6 +125,7 @@ int main(void)
         OFFSET(BP_loadflags, boot_params, hdr.loadflags);
         OFFSET(BP_hardware_subarch, boot_params, hdr.hardware_subarch);
         OFFSET(BP_version, boot_params, hdr.version);
+        OFFSET(BP_kernel_alignment, boot_params, hdr.kernel_alignment);
 
         BLANK();
         DEFINE(PAGE_SIZE_asm, PAGE_SIZE);