On 3/18/12 11:45 AM, Shea Levy wrote:
> Hello,
>
> Inlined is a patch to have the kernel read its parameters from a 
> config file when booted via the EFI boot stub without any parameters 
> passed. This patch roughly follows the plan I discussed when proposing 
> this idea, except now the file is found relative to the location of 
> the bzImage and there is no additional check to see if 
> image->parent_handle is NULL (despite the spec saying it will be NULL 
> when the image was loaded by the firmware itself, it was never NULL on 
> any of the systems I tested).
>
> Cheers,
> Shea Levy
>
> ---
>
> From 2c12b0f49831d2d96b6bdcef931794178312c288 Mon Sep 17 00:00:00 2001
> From: Shea Levy <shea@shealevy.com>
> Date: Sun, 18 Mar 2012 16:17:04 +0100
> Subject: [PATCH 1/1] x86, efi: EFI boot stub config file support
>
> When booting via the EFI boot stub, search for a file named 
> 'linux.conf' in
> the same directory as the bzImage and read the kernel command line 
> from it
> when no load options are passed.
>
> The file search should only be triggered when the bzImage is loaded 
> from the
> firmware's boot process. When loaded via an EFI shell, the load 
> options always
> contain at least one character, even if no parameters were passed at the
> prompt.
>
> Signed-off-by: Shea Levy <shea@shealevy.com>
> ---
>  arch/x86/boot/compressed/eboot.c |  146 
> ++++++++++++++++++++++++++++++++++++--
>  arch/x86/boot/compressed/eboot.h |    2 +
>  2 files changed, 143 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/boot/compressed/eboot.c 
> b/arch/x86/boot/compressed/eboot.c
> index fec216f..672ecfe 100644
> --- a/arch/x86/boot/compressed/eboot.c
> +++ b/arch/x86/boot/compressed/eboot.c
> @@ -486,14 +486,14 @@ struct initrd {
>   * kernel image.
>   */
>  static efi_status_t handle_ramdisks(efi_loaded_image_t *image,
> -                    struct setup_header *hdr)
> +                    struct setup_header *hdr,
> +                    efi_file_handle_t *fh)
>  {
>      struct initrd *initrds;
>      unsigned long initrd_addr;
>      efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
>      u64 initrd_total;
>      efi_file_io_interface_t *io;
> -    efi_file_handle_t *fh;
>      efi_status_t status;
>      int nr_initrds;
>      char *str;
> @@ -568,7 +568,7 @@ static efi_status_t 
> handle_ramdisks(efi_loaded_image_t *image,
>          *p = '\0';
>
>          /* Only open the volume once. */
> -        if (!i) {
> +        if (!fh) {
>              efi_boot_services_t *boottime;
>
>              boottime = sys_table->boottime;
> @@ -712,6 +712,7 @@ static efi_status_t make_boot_params(struct 
> boot_params *boot_params,
>      u16 *s2;
>      u8 *s1;
>      int i;
> +    efi_file_handle_t *fh = NULL;
>
>      hdr->type_of_loader = 0x21;
>
> @@ -743,14 +744,149 @@ static efi_status_t make_boot_params(struct 
> boot_params *boot_params,
>
>              *s1 = '\0';
>          }
> -    }
> +    } else {
> +        efi_char16_t config_file_name[
> +            sizeof CONFIG_FILE_NAME * sizeof(efi_char16_t)];
> +        u16 *file_path = (u16 *)image->file_path;
> +        efi_char16_t config_path[256], *config_path_position;
> +        efi_boot_services_t *boottime;
> +        efi_file_info_t *info;
> +        unsigned long info_sz = 0;
> +        u64 file_sz;
> +        efi_guid_t info_guid = EFI_FILE_INFO_ID;
> +        efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
> +        efi_file_io_interface_t *io;
> +        efi_file_handle_t *h;
> +
> +        boottime = sys_table->boottime;
> +
> +        config_path_position = config_path;
> +
> +        for (i = 0; i < sizeof CONFIG_FILE_NAME; i++)
> +            config_file_name[i] = CONFIG_FILE_NAME[i];
> +
> +        while (*file_path == 0x404) {
> +            u16 node_size = *(file_path + 1)/sizeof *file_path;
> +
> +            if (config_path_position - config_path) {
> +                if (*(file_path + 2) == '\\' &&
> +                        *(file_path - 2) == '\\') {
> +                    config_path_position--;
> +                } else if (*(file_path + 2) != '\\' &&
> +                        *(file_path - 2) != '\\') {
> +                    *config_path_position++ = '\\';
> +                }
> +            }
> +
> +            if ((config_path_position - config_path) + node_size - 3
> +                    + sizeof config_file_name
> +                    / sizeof *config_file_name
> + > sizeof config_path
> +                    / sizeof *config_path)
> +                goto end;
> +
> +            memcpy((void *)config_path_position, file_path + 2,
> +                    (node_size - 3) * sizeof *config_path);
>
> +            config_path_position += node_size - 3;
> +            file_path += node_size;
> +        }
> +
> +        while (*config_path_position != '\\' && config_path_position !=
> +                config_path)
> +            config_path_position--;
> +
> +        *config_path_position = '\\';
> +
> +        memcpy((void *)(config_path_position + 1),
> +                config_file_name,
> +                sizeof config_file_name);
> +
> +        status = efi_call_phys3(boottime->handle_protocol,
> +                image->device_handle, &fs_proto, &io);
> +
> +        if (status != EFI_SUCCESS)
> +            goto end;
> +
> +        status = efi_call_phys2(io->open_volume, io, &fh);
> +
> +        if (status != EFI_SUCCESS) {
> +            fh = NULL;
> +            goto end;
> +        }
> +
> +        status = efi_call_phys5(fh->open,
> +                fh,
> + &h,
> +                config_path,
> +                EFI_FILE_MODE_READ, (u64)0);
> +
> +        if (status != EFI_SUCCESS)
> +            goto end;
> +
> +        status = efi_call_phys4(h->get_info, h, &info_guid,
> + &info_sz, NULL);
> +
> +        if (status != EFI_BUFFER_TOO_SMALL)
> +            goto close_config_file;
> +
> +        while (status == EFI_BUFFER_TOO_SMALL) {
> +            status = efi_call_phys3(boottime->allocate_pool,
> +                    EFI_LOADER_DATA, info_sz, &info);
> +
> +            if (status != EFI_SUCCESS)
> +                goto close_config_file;
> +
> +            status = efi_call_phys4(h->get_info, h, &info_guid,
> + &info_sz, info);
> +
> +            if (status == EFI_BUFFER_TOO_SMALL)
> +                efi_call_phys1(boottime->free_pool, info);
> +        }
> +
> +        if (status != EFI_SUCCESS)
> +            goto free_config_file_info;
> +
> +        file_sz = info->file_size;
> +
> +        if (file_sz > hdr->cmdline_size)
> +            file_sz = hdr->cmdline_size;
> +
> +        options_size = file_sz + 1;
> +
> +        status = low_alloc(options_size, 1, &cmdline);
> +
> +        if (status != EFI_SUCCESS)
> +            goto free_config_file_info;
> +
> +        status = efi_call_phys3(h->read, h, &file_sz, cmdline);
> +
> +        if (status != EFI_SUCCESS)
> +            goto free_config_file_cmdline;
> +
> +        *((u8 *)cmdline + file_sz) = 0;
> +
> +        goto free_config_file_info;
> +free_config_file_cmdline:
> +        low_free(options_size, cmdline);
> +        cmdline = 0;
> +        options_size = 0;
> +free_config_file_info:
> +        efi_call_phys1(boottime->free_pool, info);
> +close_config_file:
> +        efi_call_phys1(h->close, h);
> +    }
> +end:
>      hdr->cmd_line_ptr = cmdline;
>
>      hdr->ramdisk_image = 0;
>      hdr->ramdisk_size = 0;
>
> -    status = handle_ramdisks(image, hdr);
> +    status = handle_ramdisks(image, hdr, fh);
> +
> +    if (fh)
> +        efi_call_phys1(fh->close, fh);
> +
>      if (status != EFI_SUCCESS)
>          goto free_cmdline;
>
> diff --git a/arch/x86/boot/compressed/eboot.h 
> b/arch/x86/boot/compressed/eboot.h
> index 3925166..186b4c6 100644
> --- a/arch/x86/boot/compressed/eboot.h
> +++ b/arch/x86/boot/compressed/eboot.h
> @@ -20,6 +20,8 @@
>  #define PIXEL_BLT_ONLY                    3
>  #define PIXEL_FORMAT_MAX                4
>
> +#define CONFIG_FILE_NAME "linux.conf"
> +
>  struct efi_pixel_bitmask {
>      u32 red_mask;
>      u32 green_mask;

Hmm, my mail client seems to have mangled the patch. I've attached it here.