Subject: Re: 64-bit daddr_t problems with libsa
From: David Laight <email@example.com>
Date: 01/31/2003 12:11:42
> No objections, but why are the bootxx_ffs (and I presume the _lfs
> as well) using daddr_t at all?
> That's not the data type that is in the filesystemsm ffs uses
> ufs_daddr_t when it wants to put a block number somewhere. I assume
> (but haven't checked) that LFS is similar.
It will allow you to boot from a UFS filesystem that is beyond
1TB down the disk...
I do wonder whether the the following interface would be
enough for the boot code - which only ever nees to have
a single file open etc.
ufs_mount(...); : read superblock etc
length = ufs_read_file(int inode, void *buffer, size_t buflen);
inode = ufs_scan_dir(char *name, void *buffer, size_t buflen)
To read /boot you would do:
len = ufs_read_file( 2 /* root inode */, load_tgt, ~0);
inode = ufs_scan_dir("boot", load_tgt, len);
ufs_read_file(inode, load_tgt, ~0);
/* jump into image */
call *(void (*)(void))load_tgt;
That ought to fit into almost no bytes at all.
Especially if you don't need support for double (or triple)
Could probably even get the i386 code to not need a sector/count
David Laight: firstname.lastname@example.org