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/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 2bb500a..f62c284 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -84,8 +84,11 @@
#ifdef CONFIG_RELOCATABLE
movl %ebp, %ebx
- addl $(PMD_PAGE_SIZE -1), %ebx
- andl $PMD_PAGE_MASK, %ebx
+ movl BP_kernel_alignment(%esi), %eax
+ decl %eax
+ addl %eax, %ebx
+ notl %eax
+ andl %eax, %ebx
#else
movl $LOAD_PHYSICAL_ADDR, %ebx
#endif
@@ -224,8 +227,11 @@
/* Start with the delta to where the kernel will run at. */
#ifdef CONFIG_RELOCATABLE
leaq startup_32(%rip) /* - $startup_32 */, %rbp
- addq $(PMD_PAGE_SIZE - 1), %rbp
- andq $PMD_PAGE_MASK, %rbp
+ movl BP_kernel_alignment(%rsi), %eax
+ decl %eax
+ addq %rax, %rbp
+ notq %rax
+ andq %rax, %rbp
#else
movq $LOAD_PHYSICAL_ADDR, %rbp
#endif