Re: [Libcdio-devel] About old branches of mine

[Thomas Schmitt]

Hi,

Rocky Bernstein
>     test/data/multi_extent_8k.iso        | Bin 524288 -> 122880 bytes
> I think both versions should be there. We should be testing not just how
> things are created currently, but also how they may have been created in
> the past.

I realize that i forgot to take into account your mail of
Mon, 27 Mar 2023 09:11:32 -0400.

But actually i wanted to ask back why you want to keep an ISO which was
just created a bit wasteful for its purpose.

It will never end up on a CD that gets written with write type TAO. Thus
it needs no 300 KiB of padding.
It will never be enlarged by multi-session. Thus a separate superblock
for the first session is not needed.

The padding compensates for mislead reading ahead by Linux when the
drive firmware tells questionable read capacity which is invited by a bug
in the SCSI specs.

The separate superblock would survive the writing of a next session and
stay mountable. Also it would be the starting point of the search for the
chain of session superblocks. xorriso command -toc can then tell a session
history like
  ISO session  :   1 ,        32 ,   2024199s , HOME_2022_07_07_155642
  ISO session  :   2 ,   2024256 ,     26157s , HOME_2022_07_08_155953
  ISO session  :   3 ,   2050432 ,     32162s , HOME_2022_07_09_151801
  ...
  ISO session  : 267 ,  11491200 ,     52690s , HOME_2023_03_30_193636
  ISO session  : 268 ,  11543904 ,     44883s , HOME_2023_03_31_154321
  Media summary: 268 sessions, 11584524 data blocks, 22.1g data,  976m free

Linux or libcdio are supposed to use the first superblock at LBA 0 which
always points to the newest session. So the old test ISO and the new one
are equivalent as far as libcdio is concerned.
If we keep the old ISO then there is no need to have the new one. It would
only be more waste of space.


Have a nice day :)

Thomas