ISO9660 4GB directory structures boundary limit and growisofs

Tom Evans at
Mon Apr 19 14:10:41 UTC 2010

On Mon, Apr 19, 2010 at 1:48 PM, Paul B Mahol <onemda at> wrote:
> On 4/17/10, Paul B Mahol <onemda at> wrote:
>> On Sat, Apr 17, 2010 at 4:31 PM, Tim Kientzle <kientzle at> wrote:
>>> Paul B Mahol wrote:
>>>> It is apparently not possible to make use of -use-the-force-luke=4gms
>>>> on FreeBSD when appending new session after 4GB. Mounted disk
>>>> afterwards  show nothing.
>>>> Should we allow it like linux does?
>>> Are you claiming there is a problem when FreeBSD reads such
>>> images or a problem with creating such images?  What
>>> programs are you using?
>> I burn flac files in multiple sessions, each session have separate
>> directory, on DVD+R DL MKM/003
>> After I used 4gms switch mounted fs shows nothing. (but there is >5GB of
>> data)
>> According to growisofs source BD (bluray) dont need this switch at all ...
>>> This sounds like a pretty unsurprising 32-bit truncation
>>> bug:  the filesystem structures in ISO9660 are all sector
>>> numbers so 8TB should be the natural limit (4G sectors
>>> times 2k bytes/sector).
>> I did not tested this on FreeBSD amd64 yet.
> Update: Linux shows all sessions and Windows 7 shows only first one.

>From the source code of groisofs.c:

 * - DVD+R Double Layer support;
 * - -use-the-force-luke=4gms to allow ISO9660 directory structures
 *   to cross 4GB boundary, the option is effective only with DVD+R DL
 *   and for data to be accessible under Linux isofs a kernel patch is
 *   required;

So I'm guessing it does something non standard, particularly if
windows also refuses to see the data.



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