[U-Boot] [PATCH 2/2] x86: Add support for booting Linux using the 32 bit boot protocol

Graeme Russ graeme.russ at gmail.com
Wed Nov 30 04:23:06 CET 2011


Hi Gabe,

Thanks, I've been itching for this :)

On Wed, Nov 30, 2011 at 2:11 PM, Gabe Black <gabeblack at chromium.org> wrote:
> This change conditionally modifies the zboot command so that it can use the
> 32 bit boot protocol. This is necessary because the 16 bit realmode entry
> point assumes that it can call BIOS services which neither coreboot nor
> u-boot provide.
>
> Signed-off-by: Gabe Black <gabeblack at chromium.org>
> ---
>  arch/x86/include/asm/zimage.h |    4 +-
>  arch/x86/lib/bootm.c          |    6 +++-
>  arch/x86/lib/zimage.c         |   49 +++++++++++++++++++++++++++++++---------
>  3 files changed, 44 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/include/asm/zimage.h b/arch/x86/include/asm/zimage.h
> index 1a77e00..8ee6a74 100644
> --- a/arch/x86/include/asm/zimage.h
> +++ b/arch/x86/include/asm/zimage.h
> @@ -46,8 +46,8 @@
>
>  void *load_zimage(char *image, unsigned long kernel_size,
>                  unsigned long initrd_addr, unsigned long initrd_size,
> -                 int auto_boot);
> +                 int auto_boot, void **load_address);
>
> -void boot_zimage(void *setup_base);
> +void boot_zimage(void *setup_base, void *load_address);
>
>  #endif
> diff --git a/arch/x86/lib/bootm.c b/arch/x86/lib/bootm.c
> index bac7b4f..0905809 100644
> --- a/arch/x86/lib/bootm.c
> +++ b/arch/x86/lib/bootm.c
> @@ -38,6 +38,7 @@ int do_bootm_linux(int flag, int argc, char * const argv[],
>        void            *base_ptr = NULL;
>        ulong           os_data, os_len;
>        image_header_t  *hdr;
> +       void            *load_address;
>
>  #if defined(CONFIG_FIT)
>        const void      *data;
> @@ -75,7 +76,8 @@ int do_bootm_linux(int flag, int argc, char * const argv[],
>
>  #ifdef CONFIG_CMD_ZBOOT
>        base_ptr = load_zimage((void *)os_data, os_len,
> -                       images->rd_start, images->rd_end - images->rd_start, 0);
> +                       images->rd_start, images->rd_end - images->rd_start,
> +                       0, &load_address);
>  #endif
>
>        if (NULL == base_ptr) {
> @@ -92,7 +94,7 @@ int do_bootm_linux(int flag, int argc, char * const argv[],
>        /* we assume that the kernel is in place */
>        printf("\nStarting kernel ...\n\n");
>
> -       boot_zimage(base_ptr);
> +       boot_zimage(base_ptr, load_address);
>        /* does not return */
>
>  error:
> diff --git a/arch/x86/lib/zimage.c b/arch/x86/lib/zimage.c
> index 3b33486..1003929 100644
> --- a/arch/x86/lib/zimage.c
> +++ b/arch/x86/lib/zimage.c
> @@ -83,13 +83,12 @@ static void build_command_line(char *command_line, int auto_boot)
>
>  void *load_zimage(char *image, unsigned long kernel_size,
>                  unsigned long initrd_addr, unsigned long initrd_size,
> -                 int auto_boot)
> +                 int auto_boot, void **load_address)
>  {
>        struct boot_params *setup_base;
>        int setup_size;
>        int bootproto;
>        int big_image;
> -       void *load_address;
>
>        struct boot_params *params = (struct boot_params *)image;
>        struct setup_header *hdr = &params->hdr;
> @@ -136,14 +135,23 @@ void *load_zimage(char *image, unsigned long kernel_size,
>
>        /* Determine load address */
>        if (big_image)
> -               load_address = (void *)BZIMAGE_LOAD_ADDR;
> +               *load_address = (void *)BZIMAGE_LOAD_ADDR;
>        else
> -               load_address = (void *)ZIMAGE_LOAD_ADDR;
> +               *load_address = (void *)ZIMAGE_LOAD_ADDR;
> +
> +#if defined CONFIG_ZBOOT_32
> +       printf("Building boot_params at 0x%8.8lx\n", (ulong)setup_base);
> +       memset(setup_base, 0, sizeof(*setup_base));
> +       setup_base->hdr = params->hdr;
>
> +       setup_base->e820_entries = install_e820_map(
> +               ARRAY_SIZE(setup_base->e820_map), setup_base->e820_map);

Where is  install_e820_map() defined?

> +#else
>        /* load setup */
>        printf("Moving Real-Mode Code to 0x%8.8lx (%d bytes)\n",
>               (ulong)setup_base, setup_size);
>        memmove(setup_base, image, setup_size);
> +#endif
>
>        printf("Using boot protocol version %x.%02x\n",
>               (bootproto & 0xff00) >> 8, bootproto & 0xff);
> @@ -182,7 +190,7 @@ void *load_zimage(char *image, unsigned long kernel_size,
>
>                if (hdr->setup_sects >= 15) {
>                        printf("Linux kernel version %s\n",
> -                              (char *)setup_base +
> +                              (char *)params +
>                               hdr->kernel_version + 0x200);
>                } else {
>                        printf("Setup Sectors < 15 - "
> @@ -237,17 +245,33 @@ void *load_zimage(char *image, unsigned long kernel_size,
>        build_command_line((char *)setup_base + COMMAND_LINE_OFFSET, auto_boot);
>
>        printf("Loading %czImage at address 0x%08x (%ld bytes)\n",
> -              big_image ? 'b' : ' ', (u32)load_address, kernel_size);
> +              big_image ? 'b' : ' ', (u32)*load_address, kernel_size);
>
> -
> -       memmove(load_address, image + setup_size, kernel_size);
> +       memmove(*load_address, image + setup_size, kernel_size);
>
>        /* ready for booting */
>        return setup_base;
>  }
>
> -void boot_zimage(void *setup_base)
> +void boot_zimage(void *setup_base, void *load_address)
>  {
> +#if defined CONFIG_ZBOOT_32
> +       /*
> +        * Set %ebx, %ebp, and %edi to 0, %esi to point to the boot_params
> +        * structure, and then jump to the kernel. We assume that %cs is
> +        * 0x10, 4GB flat, and read/execute, and the data segments are 0x18,
> +        * 4GB flat, and read/write. U-boot is setting them up that way for
> +        * itself in arch/i386/cpu/cpu.c.
> +        */
> +       __asm__ __volatile__ (
> +       "movl $0, %%ebp         \n"
> +       "cli                    \n"
> +       "jmp %[kernel_entry]    \n"
> +       :: [kernel_entry]"r"(load_address),
> +          [boot_params] "S"(setup_base),
> +          "b"(0), "D"(0)
> +       );
> +#else
>        struct pt_regs regs;
>
>        memset(&regs, 0, sizeof(struct pt_regs));
> @@ -258,12 +282,14 @@ void boot_zimage(void *setup_base)
>        regs.eflags = 0;
>        enter_realmode(((u32)setup_base + SETUP_START_OFFSET) >> 4, 0,
>                       &regs, &regs);
> +#endif
>  }
>
>  int do_zboot(cmd_tbl_t *cmdtp, int flag, int argc, char *const argv[])
>  {
>        void *base_ptr;
>        void *bzImage_addr = NULL;
> +       void *load_address;
>        char *s;
>        ulong bzImage_size = 0;
>
> @@ -287,7 +313,8 @@ int do_zboot(cmd_tbl_t *cmdtp, int flag, int argc, char *const argv[])
>                bzImage_size = simple_strtoul(argv[2], NULL, 16);
>
>        /* Lets look for */
> -       base_ptr = load_zimage(bzImage_addr, bzImage_size, 0, 0, 0);
> +       base_ptr = load_zimage(bzImage_addr, bzImage_size, 0, 0, 0,
> +               &load_address);
>
>        if (!base_ptr) {
>                printf("## Kernel loading failed ...\n");
> @@ -299,7 +326,7 @@ int do_zboot(cmd_tbl_t *cmdtp, int flag, int argc, char *const argv[])
>                /* we assume that the kernel is in place */
>                printf("\nStarting kernel ...\n\n");
>
> -               boot_zimage(base_ptr);
> +               boot_zimage(base_ptr, load_address);
>                /* does not return */
>        }
>
> --
> 1.7.3.1
>

Regards,

Graeme


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