linux-kernel - Re: Revert commit 5dcd14ecd4 - breaks EFI boot with SLES11 elilo.efi

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Date:	Tue, 5 Mar 2013 11:12:08 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Robin Holt <holt@....com>, hpa@....com,
	linux-kernel@...r.kernel.org
Subject: Re: Revert commit 5dcd14ecd4 - breaks EFI boot with SLES11 elilo.efi

On Tue, Mar 5, 2013 at 7:22 AM, H. Peter Anvin <hpa@...or.com> wrote:
> Yes, please do the analysis I asked for.

it uses first 2 pages in bzImage to bootparams.

then update the fields with ===> X

struct boot_params {
        struct screen_info screen_info;                 /* 0x000 */   ===> X
        struct apm_bios_info apm_bios_info;             /* 0x040 */   ===> X
        __u8  _pad2[4];                                 /* 0x054 */
        __u64  tboot_addr;                              /* 0x058 */
        struct ist_info ist_info;                       /* 0x060 */
        __u8  _pad3[16];                                /* 0x070 */
        __u8  hd0_info[16];     /* obsolete! */         /* 0x080 */   ===> X
        __u8  hd1_info[16];     /* obsolete! */         /* 0x090 */   ===> X
        struct sys_desc_table sys_desc_table;           /* 0x0a0 */   ===> X
        struct olpc_ofw_header olpc_ofw_header;         /* 0x0b0 */
        __u32 ext_ramdisk_image;                        /* 0x0c0 */
        __u32 ext_ramdisk_size;                         /* 0x0c4 */
        __u32 ext_cmd_line_ptr;                         /* 0x0c8 */
        __u8  _pad4[116];                               /* 0x0cc */
        struct edid_info edid_info;                     /* 0x140 */
        struct efi_info efi_info;                       /* 0x1c0 */   ===> X
        __u32 alt_mem_k;                                /* 0x1e0 */   ===> X
        __u32 scratch;          /* Scratch field! */    /* 0x1e4 */
        __u8  e820_entries;                             /* 0x1e8 */  ===> X
        __u8  eddbuf_entries;                           /* 0x1e9 */
        __u8  edd_mbr_sig_buf_entries;                  /* 0x1ea */
        __u8  kbd_status;                               /* 0x1eb */
        __u8  _pad5[3];                                 /* 0x1ec */
        /*
         * The sentinel is set to a nonzero value (0xff) in header.S.
         *
         * A bootloader is supposed to only take setup_header and put
         * it into a clean boot_params buffer. If it turns out that
         * it is clumsy or too generous with the buffer, it most
         * probably will pick up the sentinel variable too. The fact
         * that this variable then is still 0xff will let kernel
         * know that some variables in boot_params are invalid and
         * kernel should zero out certain portions of boot_params.
         */
        __u8  sentinel;                                 /* 0x1ef */
        __u8  _pad6[1];                                 /* 0x1f0 */
        struct setup_header hdr;    /* setup header */  /* 0x1f1 */  ===> X
        __u8  _pad7[0x290-0x1f1-sizeof(struct setup_header)];
        __u32 edd_mbr_sig_buffer[EDD_MBR_SIG_MAX];      /* 0x290 */
        struct e820entry e820_map[E820MAX];             /* 0x2d0 */  ===> X
        __u8  _pad8[48];                                /* 0xcd0 */
        struct edd_info eddbuf[EDDMAXNR];               /* 0xd00 */
        __u8  _pad9[276];                               /* 0xeec */

so sentinel will be kept as 0xff, so efi_info get cleared by kernel...

Attached patches should avoid the clearing of efi_info when elilo is used.

Do we need to clear edd and pad2 and pad3 for elilo?

Thanks

Yinghai

Download attachment "fix_elilo.patch" of type "application/octet-stream" (925 bytes)