[Oberon] Reason for 'read pio error' ?

[muller at inf.ethz.ch]

Andreas Dörr <andreas.doerr at workingobjects.de> wrote:
> I have successfully installed Bluebottle on a Dell Inspiron 7500.

Good!

> Currently I use a 5GB partition for Bluebottle. While trying to format a 
> second 5GB partition with AosFS I got an error '2820' at lba 12991229.

A disk block is 512 bytes.  So lba 12991229 translates to about 
6.2GB (6.5GB metric).  You didn't say what the disk size is, but I 
assume it is larger than this.

Looking at AosATADisks.ReadPIO, it seems error 2820 is generated when
the ERR bit is set after a command.

At what stage does this error occur?  I assume during Partitions.Format?

> Does anyone know what is a typical reason for such an error?

I'm not sure why the driver sees this ERR bit, and as you say, modern 
disks should remap bad sectors automatically.  I'm not sure if they 
can do this without OS support.  Perhaps the OS is required to retry 
a failed transfer?  But then a second Partitions.Format should work...

> The only workaround I currently know is to define a small partition that 
> includes the conspicuous block. This partition will not be used. Since the 
> number of partitions is limited this is not a very good workaround :-(

Unfortunately this is currently the only workaround, since the AosFS
file system does not handle bad blocks.  What needs to be done is:

1. detect bad blocks in Partitions.Format
2. create a file that contains all these bad blocks

This will ensure that the bad blocks are ignored by the file system.
Part 2 is file system specific.

If someone wants to attempt this, I suggest taking the relevant 
Format code from Partitions.Mod and rewriting it in a new module.

Stefan Salewski <Salewski at physnet.uni-hamburg.de> wrote:
> I think the 8GB-Limit still exist for Bluebottle and 
> ETH-Native-Oberon. This means Bios-calls are used to access the 
> harddisk, and this method is limited to the first 8 GB. I am 
> not sure if this is still true for newest Bios, but it was true 
> too for my /boot-partition of my Linux-Installation.

This is only partially true.  The boot file has to be below 8GB
if you want to boot from the partition directly (otherwise you
could use noboot.exe).

This is another project for someone.  Rewrite the OBL boot loader 
to support larger disks.

The ATA and SCSI disk drivers and the AosFS file system support 
disks up to 128GB (the next hardware limit, surpassed in ATA-5,
I think).

> I cant imagine how you will fill 5 GB with Bluebottle.

With data!

cglur at onwe.co.za wrote:
> ? number of partitions is limited ?
> Is this the Microsoft limit of 4 ?

No.  You can have 4 primary partitions per hard disk (in the MBR),
but an unlimited number of "logical drives" in an extended partition.

BTW A new partition table format is slowly being introduced
by Intel and Microsoft.  It is not yet supported by Bluebottle.
  http://developer.intel.com/technology/efi/download.htm
  http://www.microsoft.com/hwdev/tech/storage/GPT_FAQ.asp
Originally the motivation was to clean up their act for 64-bit
Windows, but I suspect they'll want to switch to the new format
for 32-bit Windows also, since the old MBR format is a mess.

> Since Micro$hit's policy is to squash all other OS's, perhaps 

Please don't resort to childish name-calling, it is counter-productive.

> For those who dare to step outside M$ limits with PC's, it's good
> to be allied with linux.  There are many soldier to clear the way for you.

It is true that a lot of information can be gleaned from Linux.
Sometimes you just have to dig quite deep for it.

-- Pieter

--
Pieter Muller, Computer Systems Institute, ETH Zurich / MCT Lab, Zurich
Native Oberon OS: http://www.oberon.ethz.ch/native/