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From: "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com>
Message-Id: <199505120158.SAA13806@gndrsh.aac.dev.com>
Subject: Re: problem for reading old CD-ROM
To: ohki@gssm.otsuka.tsukuba.ac.jp
Date: Thu, 11 May 1995 18:58:28 -0700 (PDT)
Cc: terry@cs.weber.edu, freebsd-bugs@FreeBSD.org
In-Reply-To: <199505120144.KAA00248@smri01.gssm.otsuka.tsukuba.ac.jp> from "ohki@gssm.otsuka.tsukuba.ac.jp" at May 12, 95 10:44:14 am
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> 
> 
> rgrimes>> I am not sure, I need to go check my iso 9660 spec,
> rgrimes>> but it seems to me
> rgrimes>> that 512 byte logical blocks are a violation of of the spec.
> rgrimes>> Changing
> rgrimes>> the cd9660 code to read non-conformat cd-roms, IMHO, is an ugly hack
> rgrimes>> at best.
> 
> terry> I disagree about the ability to read non-conformant CDROMs.
> terry>  Unfortunately,
> terry> there's not a sticker that they can only display if they conform, and
> terry> the public doesn't only buy them if they conform.
> 
> rgrimes>> Changing block device code to do unaligned block transfers is even
> rgrimes>> worse :-(.
> 
> terry> This I definitely agree with; if the code is going to be bastardized,
> terry> better to do the deed in the FS specific code by buffering more than
> terry> necessary in and hanging it off the in core version of the vnode after
> terry> translation instead of hanging it off the vnode in the normal place.
> 
>  I know my hacking is not a good one, and I wanted to hear opinions
>  about handling of non-conformat cd-roms from members.
> 
>  The cd-rom I tried to read is labled as
>  "This disc was mastered to ISO 9660 Standard. Level 1",
>  so I thought this is confomat cd-rom. (Is this not true?)

Refering to ISO 9660 : 1988 (E) sections 6.1.2 and 6.2.2 tell me that
a Logical Sector and Logical Block are of size 2^(n+9) meaning 2048
bytes or longer, thus a 512 byte logical block is infact a violation
of ISO 9660 : 1988 (E).

You should be able to ftp a copy of that spec from
ftp.cdrom.com:/pub/cdrom some place.  Check the faq, they might
have a pointer in there to the location of the iso spec.  Or maybe
it is only the RRIP spec you can get online.


-- 
Rod Grimes                                      rgrimes@gndrsh.aac.dev.com
Accurate Automation Company                   Custom computers for FreeBSD