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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH RFC 5/7] xen/x86: Add multiboot2 protocol support
On 09/08/14 00:04, Daniel Kiper wrote:
> Add multiboot2 protocol support. This way we are laying the foundation
> for EFI + GRUB2 + Xen development.
>
> Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
> ---
> xen/arch/x86/boot/head.S | 112
> ++++++++++++++++++++++++++++++++++++++++++++-
> xen/arch/x86/boot/reloc.c | 103 ++++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 212 insertions(+), 3 deletions(-)
>
> diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
> index 79bce3c..f0ea6d0 100644
> --- a/xen/arch/x86/boot/head.S
> +++ b/xen/arch/x86/boot/head.S
> @@ -1,5 +1,6 @@
> #include <xen/config.h>
> #include <xen/multiboot.h>
> +#include <xen/multiboot2.h>
> #include <public/xen.h>
> #include <asm/asm_defns.h>
> #include <asm/desc.h>
> @@ -33,6 +34,68 @@ ENTRY(start)
> /* Checksum: must be the negated sum of the first two fields. */
> .long -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
>
> +/*** MULTIBOOT2 HEADER ****/
> +/* Some ideas are taken from grub-2.00/grub-core/tests/boot/kernel-i386.S
> file. */
> + .align MULTIBOOT2_HEADER_ALIGN
> +
> +multiboot2_header:
> + /* Magic number indicating a Multiboot2 header. */
> + .long MULTIBOOT2_HEADER_MAGIC
> + /* Architecture: i386. */
> + .long MULTIBOOT2_ARCHITECTURE_I386
> + /* Multiboot2 header length. */
> + .long multiboot2_header_end - multiboot2_header
> + /* Multiboot2 header checksum. */
> + .long -(MULTIBOOT2_HEADER_MAGIC + MULTIBOOT2_ARCHITECTURE_I386 + \
> + (multiboot2_header_end - multiboot2_header))
> +
> + /* Multiboot2 tags... */
> +multiboot2_info_req:
> + /* Multiboot2 information request tag. */
> + .short MULTIBOOT2_HEADER_TAG_INFORMATION_REQUEST
> + .short MULTIBOOT2_HEADER_TAG_REQUIRED
> + .long multiboot2_info_req_end - multiboot2_info_req
> + .long MULTIBOOT2_TAG_TYPE_MMAP
> +multiboot2_info_req_end:
> +
> + /*
> + * Align Xen image and modules at page boundry.
> + *
> + * .balignl MULTIBOOT2_TAG_ALIGN, MULTIBOOT2_TAG_TYPE_END is a hack
> + * to avoid bug related to Multiboot2 information request tag in
> earlier
> + * versions of GRUB2.
> + *
> + * DO NOT MOVE THIS TAG! ANY CHANGE HERE MAY BREAK COMPATIBILITY
> + * WITH EARLIER GRUB2 VERSIONS!
> + */
> + .balignl MULTIBOOT2_TAG_ALIGN, MULTIBOOT2_TAG_TYPE_END
> + .short MULTIBOOT2_HEADER_TAG_MODULE_ALIGN
> + .short MULTIBOOT2_HEADER_TAG_REQUIRED
> + .long 8 /* Tag size. */
> +
> + /* Console flags tag. */
> + .align MULTIBOOT2_TAG_ALIGN
> + .short MULTIBOOT2_HEADER_TAG_CONSOLE_FLAGS
> + .short MULTIBOOT2_HEADER_TAG_OPTIONAL
> + .long 12 /* Tag size. */
> + .long MULTIBOOT2_CONSOLE_FLAGS_EGA_TEXT_SUPPORTED
> +
> + /* Framebuffer tag. */
> + .align MULTIBOOT2_TAG_ALIGN
> + .short MULTIBOOT2_HEADER_TAG_FRAMEBUFFER
> + .short MULTIBOOT2_HEADER_TAG_OPTIONAL
> + .long 20 /* Tag size. */
> + .long 0 /* Number of the columns - no preference. */
> + .long 0 /* Number of the lines - no preference. */
> + .long 0 /* Number of bits per pixel - no preference. */
> +
> + /* Multiboot2 header end tag. */
> + .align MULTIBOOT2_TAG_ALIGN
> + .short MULTIBOOT2_HEADER_TAG_END
> + .short 0
> + .long 8 /* Tag size. */
> +multiboot2_header_end:
> +
> .section .init.rodata, "a", @progbits
> .align 4
>
> @@ -81,10 +144,55 @@ __start:
> mov %ecx,%es
> mov %ecx,%ss
>
> + /* Set mem_lower to 0 */
> + xor %edx,%edx
> +
How does this affect mem_lower? it doesn't appear relevant in context.
> /* Check for Multiboot bootloader */
> - cmp $0x2BADB002,%eax
> - jne not_multiboot
> + cmp $MULTIBOOT_BOOTLOADER_MAGIC,%eax
> + je 1f
This $MULTIBOOT_BOOTLOADER_MAGIC should probably be separate, as there
are other bits of code which should use multiboot manifest constants.
It looks as if this should be "je multiboot1_entry" ...
> +
> + /* Check for Multiboot2 bootloader */
> + cmp $MULTIBOOT2_BOOTLOADER_MAGIC,%eax
> + je 2f
> +
> + jmp not_multiboot
> +
> +1:
> + /* Get mem_lower from Multiboot information */
> + testb $MBI_MEMLIMITS,(%ebx)
> + jz 0f /* not available? BDA value will be fine
> */
>
> + mov 4(%ebx),%edx
> + shl $10-4,%edx
> + jmp 0f
and these 0f's should be "setup_trampoline" or similar. You have also
removed some sanity checks of the multiboot information, which need
reintroducing.
> +
> +2:
This 2 should be "multiboot2_entry"
> + /* Get Multiboot2 information address */
> + mov %ebx,%ecx
> + add $8,%ecx
Any manifest constants for this, or at least a reference to some
documentation describing how the tags are laid out?
> +
> +3:
> + /* Get mem_lower from Multiboot2 information */
> + cmpl $MULTIBOOT2_TAG_TYPE_BASIC_MEMINFO,(%ecx)
> + jne 4f
> +
> + mov 8(%ecx),%edx
> + shl $10-4,%edx
> + jmp 5f
BASIC_MEMINFO is the only tag we look for. No need to spin through all
of them if we found it. Also, needs the same sanity checking as the
multiboot1 information.
~Andrew
> +
> +4:
> + /* Is it the end of Multiboot2 information? */
> + cmpl $MULTIBOOT2_TAG_TYPE_END,(%ecx)
> + je 0f
> +
> +5:
> + /* Go to next Multiboot2 information tag */
> + add 4(%ecx),%ecx
> + add $(MULTIBOOT2_TAG_ALIGN-1),%ecx
> + and $~(MULTIBOOT2_TAG_ALIGN-1),%ecx
> + jmp 3b
> +
> +0:
> /* Set up trampoline segment 64k below EBDA */
> movzwl 0x40e,%ecx /* EBDA segment */
> cmp $0xa000,%ecx /* sanity check (high) */
> diff --git a/xen/arch/x86/boot/reloc.c b/xen/arch/x86/boot/reloc.c
> index 29f4887..eaf3226 100644
> --- a/xen/arch/x86/boot/reloc.c
> +++ b/xen/arch/x86/boot/reloc.c
> @@ -18,8 +18,12 @@ typedef unsigned long u32;
> typedef unsigned long long u64;
>
> #include "../../../include/xen/multiboot.h"
> +#include "../../../include/xen/multiboot2.h"
> #include "../../../include/asm/mbd.h"
>
> +#define ALIGN_UP(addr, align) \
> + ((addr + (typeof(addr))align - 1) & ~((typeof(addr))align -
> 1))
> +
> /*
> * __HERE__ IS TRUE ENTRY POINT!!!
> *
> @@ -144,6 +148,100 @@ static mbd_t *mb_mbd(mbd_t *mbd, multiboot_info_t *mbi)
> return mbd;
> }
>
> +static mbd_t *mb2_mbd(mbd_t *mbd, void *mbi)
> +{
> + int i, mod_idx = 0;
> + memory_map_t *mmap_dst;
> + multiboot2_memory_map_t *mmap_src;
> + multiboot2_tag_t *tag;
> + u32 ptr;
> + boot_module_t *mbd_mods;
> +
> + /* Skip Multiboot2 information fixed part. */
> + tag = mbi + sizeof(u32) * 2;
> +
> + while ( 1 )
> + {
> + if ( tag->type == MULTIBOOT2_TAG_TYPE_MODULE )
> + ++mbd->mods_nr;
> + else if ( tag->type == MULTIBOOT2_TAG_TYPE_END )
> + {
> + mbd->mods = alloc_struct(mbd->mods_nr * sizeof(boot_module_t));
> + mbd_mods = (boot_module_t *)mbd->mods;
> + break;
> + }
> +
> + /* Go to next Multiboot2 information tag. */
> + tag = (multiboot2_tag_t *)(ALIGN_UP((u32)tag + tag->size,
> MULTIBOOT2_TAG_ALIGN));
> + }
> +
> + /* Skip Multiboot2 information fixed part. */
> + tag = mbi + sizeof(u32) * 2;
> +
> + while ( 1 )
> + {
> + switch ( tag->type )
> + {
> + case MULTIBOOT2_TAG_TYPE_BOOT_LOADER_NAME:
> + ptr = (u32)((multiboot2_tag_string_t *)tag)->string;
> + mbd->boot_loader_name = copy_string(ptr);
> + break;
> +
> + case MULTIBOOT2_TAG_TYPE_CMDLINE:
> + ptr = (u32)((multiboot2_tag_string_t *)tag)->string;
> + mbd->cmdline = copy_string(ptr);
> + break;
> +
> + case MULTIBOOT2_TAG_TYPE_BASIC_MEMINFO:
> + mbd->mem_lower = ((multiboot2_tag_basic_meminfo_t
> *)tag)->mem_lower;
> + mbd->mem_upper = ((multiboot2_tag_basic_meminfo_t
> *)tag)->mem_upper;
> + break;
> +
> + case MULTIBOOT2_TAG_TYPE_MMAP:
> + mbd->mmap_size = ((multiboot2_tag_mmap_t *)tag)->size;
> + mbd->mmap_size -= sizeof(multiboot2_tag_mmap_t);
> + mbd->mmap_size += sizeof(((multiboot2_tag_mmap_t){0}).entries);
> + mbd->mmap_size /= ((multiboot2_tag_mmap_t *)tag)->entry_size;
> + mbd->mmap_size *= sizeof(memory_map_t);
> +
> + mbd->mmap = alloc_struct(mbd->mmap_size);
> +
> + mmap_src = ((multiboot2_tag_mmap_t *)tag)->entries;
> + mmap_dst = (memory_map_t *)mbd->mmap;
> +
> + for (i = 0; i < mbd->mmap_size / sizeof(memory_map_t); ++i)
> + {
> + mmap_dst[i].size = sizeof(memory_map_t);
> + mmap_dst[i].size -= sizeof(((memory_map_t){0}).size);
> + mmap_dst[i].base_addr_low = (u32)mmap_src[i].addr;
> + mmap_dst[i].base_addr_high = (u32)(mmap_src[i].addr >> 32);
> + mmap_dst[i].length_low = (u32)mmap_src[i].len;
> + mmap_dst[i].length_high = (u32)(mmap_src[i].len >> 32);
> + mmap_dst[i].type = mmap_src[i].type;
> + }
> + break;
> +
> + case MULTIBOOT2_TAG_TYPE_MODULE:
> + mbd_mods[mod_idx].start = (u32)((multiboot2_tag_module_t
> *)tag)->mod_start;
> + mbd_mods[mod_idx].end = (u32)((multiboot2_tag_module_t
> *)tag)->mod_end;
> + ptr = (u32)((multiboot2_tag_module_t *)tag)->cmdline;
> + mbd_mods[mod_idx].cmdline = copy_string(ptr);
> + mbd_mods[mod_idx].relocated = 0;
> + ++mod_idx;
> + break;
> +
> + case MULTIBOOT2_TAG_TYPE_END:
> + return mbd;
> +
> + default:
> + break;
> + }
> +
> + /* Go to next Multiboot2 information tag. */
> + tag = (multiboot2_tag_t *)(ALIGN_UP((u32)tag + tag->size,
> MULTIBOOT2_TAG_ALIGN));
> + }
> +}
> +
> /*
> * __THIS__ IS NOT ENTRY POINT!!!
> * PLEASE LOOK AT THE BEGINNING OF THIS FILE!!!
> @@ -158,5 +256,8 @@ mbd_t *__reloc(void *mbi, u32 mb_magic)
> mbd = (mbd_t *)alloc_struct(sizeof(mbd_t));
> zero_struct((u32)mbd, sizeof(mbd_t));
>
> - return mb_mbd(mbd, mbi);
> + if ( mb_magic == MULTIBOOT_BOOTLOADER_MAGIC )
> + return mb_mbd(mbd, mbi);
> + else
> + return mb2_mbd(mbd, mbi);
> }
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