[syslinux] extlinux vs ext4 64 bit

[Colin Walters]

Hi,

It looks like extlinux's code doesn't have support for the "64bit" 
feature of ext4:

extlinux:

struct ext2_group_desc {
...
    uint32_t bg_inode_table;	/* Inodes table block */
...
}

ext4:

struct ext4_group_desc {
    ...
    uint32_t bg_inode_table_lo;	/* Inodes table block */
    ...
    uint32_t bg_inode_table_hi;	/* Inodes table block MSB */
}


I'm seeing an issue where sometimes the syslinux.cfg my userspace code 
is writing is ending up with the high bits set for the block group, 
with the symptom that extlinux can't find syslinux.cfg on boot, which 
is pretty catastrophic.

Is the bug here that our installer is creating a /boot filesystem with 
the 64 bit flag set, or should we teach extlinux how to read this?

Is there any documentation on the recommended "mkfs" flags to use for 
extlinux?  Any other features that should be turned off?