[syslinux] Rock Ridge

[H. Peter Anvin]

On 04/01/2013 12:10 AM, Thomas Schmitt wrote:
> 
> XXX: Is there already a reader for 32-bit MSB or LSB in the syslinux code ?
>      (iso9660.c seems to flatly assume that it runs on little-endian int.)
> 
> I re-invented byte-to-word translation in susp_rr.c.
> iso9660.c had no such gesture as example. It rather picks the
> little-endian byte strings of the 32-bit numbers from the ISO
> and uses them directly as integers.
> 
> I understand syslinux is x86-only.
> Nevertheless, my hairs are raised when i see that gesture.
> One could replace all calls of susp_rr_read_msb() by the direct
> use of the bytes which are four byte positions before the
> big-endian byte strings wich i submit to susp_rr_read_msb().
> E.g.:
>         iter->next_lba = susp_rr_read_msb(u_entry + 8, 4);
> to
>         iter->next_lba = *((block_t *) u_entry + 4);
> 
> But as it is now, susp_rr.c should be easily portable to big-endian
> processors.
> 

Yes, this is something that needs to be fixed in our codebase, but is
somewhat further down the line.  All the near term porting targets are
littleendian.  Implicit unaligned access is also an issue.

> 
> -----------------------------------------------------------------
> 
> I see you commited the code.
> This will make the file names in Rock Ridge enhanced ISO images
> case-sensitive.
> 
> E.g. Apple HFS is addicted to case-insensitivity because the
> users learned not to care for uppercase or lowercase.
> Is it possible that the syslinux community already suffers from
> a similar addiction to case-less ISO 9660 ?
> 
> Is there the need for an option that disables Rock Ridge
> interpretation ? (Like with mount -o norock)
> 

I don't think this will be an issue for Rock Ridge.  We don't really
need a mount option, either, because it is usually quite obvious to the
generator of the disc image if the boot suddenly doesn't work.

It is probably worth highlighting, though, since it may affect some
people's scripts.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.