Grub-install fails to install core.img to boot partition

Question

I am trying to reinstall Arch onto a Dell Precision T3600 workstation, where it used to work fine, but I am stuck at the booloader step.
Details:
1. I have only one disk, partioned with gpt.
2. I am using Grub with Bios
3. As per installation instructions (preliminary requirements, BIOS systems), I created a 1007KiB boot partition at the beginning of the disk, of type ef02.
    The partition (which is umber 5 in my partition table) goes from sector 34 to sector 2047
4. I mounted the root partition to /mnt, arch-chroot'd into it, and ran
# grub-install --target=i386-pc --recheck --debug /dev/sdx
# grub-mkconfig -o /boot/grub/grub.cfg
5. I generated the /boot/grub.cfg file with the recommended
# grub-mkconfig -o /boot/grub/grub.cfg
Results:
when I try to boot, grub starts, but it cannot find anything to boot from and drops me into its shell.
Furthermore (this may be unrelated), when I take a look at the dis again (after rebooting from the install disk), I see that the gpt partition table is corrupted. Exact message  from gdisk is:
Caution: invalid backup GPT header, but valid main header: regenerating backup header from main header:
Partition table scan:
MBR: protective
BSD: not present
APM: not present
GPT: damaged
Can anyone tell me where I am going wrong? The Installation manual is not very explicit on how to deal with the (very small) boot partition. Is grub-install supposed to create the core.img file even when the partition is not mounted? Or should it be mounted. It certainly cannot contain eveyrthing that goes into /boot (which is over 100Mb).
Thanks for the help

Answer 1

Head_on_a_Stick wrote:
Your partition table is corrupted; you could clear it using:
# dd if=/dev/zero of=/dev/sd<x> bs=512 count=1; sync
Then use gdisk to recreate your partition table and re-install.
Alternatively, you could ask gdisk to re-create the backup GPT header from the main header: start up the program & press "r" followed by "d".
I had already fixed the partition table exactly as you suggested---sorry for not having been clear. It still does not boot. 
Head_on_a_Stick wrote:
Your partition table is corrupted; you could clear it using:
If it still will not boot, post your /boot/grub/grub.cfg along with the output of:
# gdisk -l /dev/sd<x>
lsblk -f
Here they are:
/boot/grub.cfg:
# DO NOT EDIT THIS FILE
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
### BEGIN /etc/grub.d/00_header ###
insmod part_gpt
insmod part_msdos
if [ -s $prefix/grubenv ]; then
load_env
fi
if [ "${next_entry}" ] ; then
set default="${next_entry}"
set next_entry=
save_env next_entry
set boot_once=true
else
set default="0"
fi
if [ x"${feature_menuentry_id}" = xy ]; then
menuentry_id_option="--id"
else
menuentry_id_option=""
fi
export menuentry_id_option
if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi
function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
function load_video {
if [ x$feature_all_video_module = xy ]; then
insmod all_video
else
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
fi
if [ x$feature_default_font_path = xy ] ; then
font=unicode
else
insmod part_gpt
insmod ext2
set root='hd0,gpt3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt3 --hint-efi=hd0,gpt3 --hint-baremetal=ahci0,gpt3 74c69286-1775-44de-90c8-3834585da6b6
else
search --no-floppy --fs-uuid --set=root 74c69286-1775-44de-90c8-3834585da6b6
fi
font="/usr/share/grub/unicode.pf2"
fi
if loadfont $font ; then
set gfxmode=auto
load_video
insmod gfxterm
set locale_dir=$prefix/locale
set lang=en_US
insmod gettext
fi
terminal_input console
terminal_output gfxterm
if [ x$feature_timeout_style = xy ] ; then
set timeout_style=menu
set timeout=5
# Fallback normal timeout code in case the timeout_style feature is
# unavailable.
else
set timeout=5
fi
### END /etc/grub.d/00_header ###
### BEGIN /etc/grub.d/10_linux ###
### END /etc/grub.d/10_linux ###
### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###
### BEGIN /etc/grub.d/30_os-prober ###
### END /etc/grub.d/30_os-prober ###
### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###
### BEGIN /etc/grub.d/41_custom ###
if [ -f ${config_directory}/custom.cfg ]; then
source ${config_directory}/custom.cfg
elif [ -z "${config_directory}" -a -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###
### BEGIN /etc/grub.d/60_memtest86+ ###
### END /etc/grub.d/60_memtest86+ ###
lsblk -f (sda1 is the swap partition, sda5 is the boot partition):
NAME FSTYPE LABEL UUID MOUNTPOINT
sda
sda1
sda3 /
sda4 /home
sda5
sr0
loop0
loop1
arch_root-image /etc/resolv.conf
loop2
arch_root-image /etc/resolv.conf
Finally, here is the partition table from gdisk -l
GPT fdisk (gdisk) version 0.8.10
Partition table scan:
MBR: protective
BSD: not present
APM: not present
GPT: present
Found valid GPT with protective MBR; using GPT.
Disk /dev/sda: 1953525168 sectors, 931.5 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 8B675D08-1A4A-44D3-ADC3-A7763E331455
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 1953525134
Partitions will be aligned on 8-sector boundaries
Total free space is 0 sectors (0 bytes)
Number Start (sector) End (sector) Size Code Name
1 2048 67112959 32.0 GiB 8200 Linux swap
3 67112960 276828159 100.0 GiB 8300 Linux filesystem
4 276828160 1953525134 799.5 GiB 8300 Linux filesystem
5 34 2047 1007.0 KiB EF02 BIOS boot partition