Re: hfsprogs: Removal of sys/sysctl.h
To come back to my incorrect sha256sum, I downloaded the iso yesterday. It was the image created on 7.11.2020. I checked against the shasums of the 'current' iso, thinking that the one of yesterday was the 'current' one. I did not know that there is a newly spinned iso, from the 8th of November in the meantime. So the iso I had was good, but from the 7th. I tried not both the 7th and 8th of November, both isos fail to be mounted.
On Sun, 8 Nov 2020 16:51:45 +0100
Jeroen Diederen <jjhdiederen@zonnet.nl> wrote:
> Hi!
>
> I tried again, checksummed the iso, all correct. I burnt the iso on the usual G5 iMac, also on a newer MacBook Pro.
> I tried the CD-R's in my PowerBook G5 as well as in my iBook G4. Nothing works. I always get the same error that it cannot mount the CDROM.
> Can you guys try it please? I am lost here.
>
> Jeroen
>
> On Sun, 8 Nov 2020 16:15:40 +0100
> Jeroen Diederen <jjhdiederen@zonnet.nl> wrote:
>
> > Hi all,
> >
> > I burn the iso again as Thomas suggested with this command:
> >
> > > xorriso -as cdrecord \
> > > -v dev=/dev/sr0 blank=as_needed -eject padsize=300k \
> > > -sao debian-10.0.0-powerpc-NETINST-1.iso
> >
> > If I boot and try to mount the CDROM it fails again to mount the CDROM but I don't see the kernel messages as before. I mean, these ones:
> >
> > > > kernel: [timestamp] sr 1:0:0:0: [sr0] tag#0 Sense Key : Illegal Request
> > > > kernel: [timestamp] sr 1:0:0:0: [sr0] tag#0 Add. Sense: Illegal mode for
> > > > this track
> > > > ...
> > > > kernel: [timestamp] attempt to access beyond end device
> > > > kernel: [timestamp] sr0: rw=0, want 640412, limit 640408
> >
> > So Thomas was right about that one. I tried several ways of burning this image now, always failing to be mounted.
> > I also tried an iBook G4, with the same result. So, I tried to do a sha512sum on the iso and it turned about the be incorrect.
> > Sorry to bother you guys, I will download the iso again and try again to see if it mounts now, with a correct iso.
> >
> > Jeroen
> >
> >
> > On Sun, 08 Nov 2020 15:10:55 +0100
> > "Thomas Schmitt" <scdbackup@gmx.net> wrote:
> >
> > > Hi,
> > >
> > > Jeroen Diederen wrote:
> > > > kernel: [timestamp] sr 1:0:0:0: [sr0] tag#0 Sense Key : Illegal Request
> > > > kernel: [timestamp] sr 1:0:0:0: [sr0] tag#0 Add. Sense: Illegal mode for
> > > > this track
> > > > ...
> > > > kernel: [timestamp] attempt to access beyond end device
> > > > kernel: [timestamp] sr0: rw=0, want 640412, limit 640408
> > >
> > > This could be the TAO CD readahead bug with a drive which cooperates
> > > badly with an obscure remedy in the kernel.
> > > Preconditions for the bug are:
> > > - CD-R or CD-RW medium, not DVD, not BD.
> > > - Write type was Track-At-Once (which is default with cdrecord and wodim).
> > >
> > > The remedy, which only works beginning with the next read attempt, can be
> > > seen in
> > > https://github.com/torvalds/linux/blob/master/drivers/scsi/sr.c
> > > under the false statement
> > > * The SCSI specification allows for the value
> > > * returned by READ CAPACITY to be up to 75 2K
> > > * sectors past the last readable block.
> > > If it works well, then it reduces the registered size of the medium
> > > (ioctl(BLKGETSIZE), lsblk -o SIZE) by 4 KiB. It is know to work better
> > > if the number of 2K blocks of the readable range is divisible by 2.
> > >
> > > In our case we have 160103 2K blocks and it looks like overcorrection:
> > >
> > > debian-10.0.0-powerpc-NETINST-1.iso of yesterday (2020110715225600)
> > > has 327890944 bytes i.e. 640412 blocks of 512 bytes.
> > > So above "want" is already beyond the end of the ISO but "limit" is inside.
> > > "want" would match the initial perception mistake of the kernel, which
> > > would be with the TAO bug 640416 or 640420 blocks, and an overshooting
> > > correction to 640408 blocks.
> > > The read access to the very end usually happens when software lookings
> > > for a GPT backup block or for an UDF anchor block.
> > >
> > >
> > > There are various rumors around this bug, but mine is provable and backed
> > > by more optical drives than the others' together. >:]
> > >
> > > Normally it gets circumvented by a adding 300 KiB of padding at the end of
> > > the CD track. If my theory is right, then no padding was added to this CD.
> > > How exactly did you burn the it ?
> > >
> > > If the burn software offers write type Session-At-Once (SAO) then burn
> > > again using this option.
> > >
> > > E.g. xorriso with explicit SAO (it uses it by default if possible)
> > > and padding:
> > >
> > > xorriso -as cdrecord \
> > > -v dev=/dev/sr0 blank=as_needed -eject padsize=300k \
> > > -sao debian-10.0.0-powerpc-NETINST-1.iso
> > >
> > > The padding might lead to success even if my theory is wrong, because if
> > > the drive would systematically underestimate SAO CDs, then the padding
> > > would sacrifice itself to the mistake like a zinc anode does to salt water.
> > >
> > > So in case of success, it would be interesting to see whether a CD burnt
> > > without option
> > > padsize=300k
> > > is mountable too, and whether a CD burnt by TAO without padding fails:
> > >
> > > xorriso -as cdrecord \
> > > -v dev=/dev/sr0 blank=as_needed -eject \
> > > -tao debian-10.0.0-powerpc-NETINST-1.iso
> > >
> > > -------------------------------------------------------------------------
> > >
> > > If this all turns out to be really the old readahed bug, does anybody here
> > > have enough reputation in linux-scsi to get a fix committed, which i have
> > > ready as set of
> > > [PATCH 0/3] Fix the old CD read-ahead bug for media with a single TAO track
> > > [PATCH 1/3] cdrom: export cdrom_mmc3_profile()
> > > [PATCH 2/3] sr: provide a test for readability of sectors as data blocks
> > > [PATCH 3/3] sr: detect CD TAO Run-out blocks and correct device capacity
> > > if needed
> > > Currently based on 5.9-rc2. Works fine with various drives.
> > > Lengthy cover letter and commit messages. Like this mail. Sorry for that.
> > >
> > >
> > > Have a nice day :)
> > >
> > > Thomas
> > >
> >
> >
> > --
> > Jeroen Diederen <jjhdiederen@zonnet.nl>
> >
>
>
> --
> Jeroen Diederen <jjhdiederen@zonnet.nl>
--
Jeroen Diederen <jjhdiederen@zonnet.nl>
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