RFC: Changing default partition type for linux/ppc

RFC: Changing default partition type for linux/ppc

[Benjamin Herrenschmidt]

Hi all !

Currently, the default partition type used by Linux/PPC on mac partition
maps is Apple_UNIX_SVR2. This is historically the type used by Apple's A/
UX for its own partitions. However, I don't like it since it gives no
indication on the type of filesystem on the partition, and I see no
reason to keep it.

So I suggest moving to Linux_ext2, Linux_swap, or maybe simply Linux and
Linux_swap (since ext2 is not the only filesystem Linux may put on
these). Using a different type for swap would help avoiding confusion.

If everyone is ok, we can then update pdisk, and on my side, I'll update
the kernel's root-auto-detect mecanism to take this into account. (The
kernel will currently find by itself a root partition if it has the above
type and the name "root" and no root= option was specified by the bootloader).

Any comments ?

Ben.


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Re: RFC: Changing default partition type for linux/ppc

[Iain Sandoe]

> Currently, the default partition type used by Linux/PPC on mac partition
> maps is Apple_UNIX_SVR2. This is historically the type used by Apple's A/
> UX for its own partitions. However, I don't like it since it gives no
> indication on the type of filesystem on the partition, and I see no
> reason to keep it.

This is a great idea - the Apple_UNIX_SVR2 bit is confusing at first.

- apart from the desire to have an 'easy to use' partition tool on the MacOS
side - for non-kernel-hackers (see Drive Partition thread).

What chance of getting Apple to support this move?

> So I suggest moving to Linux_ext2, Linux_swap, or maybe simply Linux and
> Linux_swap (since ext2 is not the only filesystem Linux may put on
> these). Using a different type for swap would help avoiding confusion.

What prospect of sharing swap space between MacOS X and linux in dual/multi
boot machines?

Iain.

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Re: RFC: Changing default partition type for linux/ppc

[Hollis Blanchard]

Iain Sandoe wrote:
>
> > Currently, the default partition type used by Linux/PPC on mac partition
> > maps is Apple_UNIX_SVR2. This is historically the type used by Apple's A/
> > UX for its own partitions. However, I don't like it since it gives no
> > indication on the type of filesystem on the partition, and I see no
> > reason to keep it.

[snip]

> What chance of getting Apple to support this move?

I would estimate the odds are somewhere between slim and none. Feel free
to email leadership@apple.com.

Of course I think we all know it's not that important either. Drive
Setup's Linux support came a few years late, and still is lacking a bit.
With Apple's new interest in Unix it's possible they might care (but
also possible that they'd have no interest in interoperating with
inferior Unices ;). Of course, I imagine they're pretty busy with their
own Unix - not much time to worry about working with other people's.

> > So I suggest moving to Linux_ext2, Linux_swap, or maybe simply Linux and
> > Linux_swap (since ext2 is not the only filesystem Linux may put on
> > these). Using a different type for swap would help avoiding confusion.

I think "Linux" and "Linux_swap" would be a good idea, especially since
some ext2 alternatives seem to be getting closer.

> What prospect of sharing swap space between MacOS X and linux in dual/multi
> boot machines?

I don't know the details, but I know that you must run mkswap on a new
swap partition. Since I don't imagine any particular effort has been put
in to keeping Linux and BSD mkswap's compatible, I doubt it would be
possible.

-Hollis

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Re: RFC: Changing default partition type for linux/ppc

[Tom Gall]

Benjamin Herrenschmidt wrote:

> Hi all !

Greets!

> So I suggest moving to Linux_ext2, Linux_swap, or maybe simply Linux and
> Linux_swap (since ext2 is not the only filesystem Linux may put on
> these). Using a different type for swap would help avoiding confusion.

I agree. I think this is a good step. However there's the obvious interoperability
problems with MacOS, OS X etc... Hopefully Apple's OSes wouldn't do anything evil
to the partition they don't recognize.

Regards,

Tom

Tom Gall - PowerPC Linux Team    "Where's the ka-boom? There was
Linux Technology Center           supposed to be an earth
(w) tom_gall@vnet.ibm.com         shattering ka-boom!"
(w) 507-253-4558                 -- Marvin Martian
(h) tgall@uswest.net
http://oss.software.ibm.com/developerworks/opensource/linux


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Re: RFC: Changing default partition type for linux/ppc

[Olaf Hering]

On Fri, Jul 07, Tom Gall wrote:

>
> Benjamin Herrenschmidt wrote:
>
> > Hi all !
>
> Greets!
>
> > So I suggest moving to Linux_ext2, Linux_swap, or maybe simply Linux and
> > Linux_swap (since ext2 is not the only filesystem Linux may put on
> > these). Using a different type for swap would help avoiding confusion.
>
> I agree. I think this is a good step. However there's the obvious interoperability
> problems with MacOS, OS X etc... Hopefully Apple's OSes wouldn't do anything evil
> to the partition they don't recognize.

As someone real important said a couple of weeks ago:
Don't trust them.


You know the slogan of Apple ;)



Gruss Olaf

--
 $ man clone

BUGS
       Main feature not yet implemented...

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Re: RFC: Changing default partition type for linux/ppc

[Hollis Blanchard]

Tom Gall wrote:
>
> Benjamin Herrenschmidt wrote:
> >
> > So I suggest moving to Linux_ext2, Linux_swap, or maybe simply Linux and
> > Linux_swap (since ext2 is not the only filesystem Linux may put on
> > these). Using a different type for swap would help avoiding confusion.
>
> I agree. I think this is a good step. However there's the obvious interoperability
> problems with MacOS, OS X etc... Hopefully Apple's OSes wouldn't do anything evil
> to the partition they don't recognize.

Well, they don't at this point. For example in partitioning tool in
LinuxPPC 2000, LinuxPPC Inc decided it would be better to use the type
"Linux_PPC". This works (in that nothing gets overwritten, corrupted,
etc) but has the disadvantage that no other software knows anything
about that type.

If you were writing software it would be pretty poor form to find data
you didn't understand and decide to "fix" it. I know there are programs
like that out there (if you look at
http://www.win.tue.nl/~aeb/partitions/partition_types-1.html it seems
there is a rich history of them), but Apple seems to be doing well in
that regard so far...

Of course, everything may change with OS X but I would hope they don't
get malicious all of a sudden.

-Hollis

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Re: RFC: Changing default partition type for linux/ppc

[Eric Valette]

Benjamin Herrenschmidt wrote:
>
> Hi all !
>
> Currently, the default partition type used by Linux/PPC on mac partition
> maps is Apple_UNIX_SVR2. This is historically the type used by Apple's A/
> UX for its own partitions. However, I don't like it since it gives no
> indication on the type of filesystem on the partition, and I see no
> reason to keep it.
>
> So I suggest moving to Linux_ext2, Linux_swap, or maybe simply Linux and
> Linux_swap (since ext2 is not the only filesystem Linux may put on
> these). Using a different type for swap would help avoiding confusion.
>
> If everyone is ok, we can then update pdisk, and on my side, I'll update
> the kernel's root-auto-detect mecanism to take this into account. (The
> kernel will currently find by itself a root partition if it has the above
> type and the name "root" and no root= option was specified by the bootloader).
>
> Any comments ?

Do not forget Prep Machines that have already a specific type of
partition that is already recognised by cfdisk...

--
   __
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Re: RFC: Changing default partition type for linux/ppc

[Geert Uytterhoeven]

On Fri, 7 Jul 2000, Hollis Blanchard wrote:
> > What prospect of sharing swap space between MacOS X and linux in dual/multi
> > boot machines?
>
> I don't know the details, but I know that you must run mkswap on a new
> swap partition. Since I don't imagine any particular effort has been put
> in to keeping Linux and BSD mkswap's compatible, I doubt it would be
> possible.

Then run `mkswap' (or whatever it's called in your-other-OS) in one of the
boot scripts.

I've been using a similar scheme to share the swap partition for Linux/m68k
and AmigaOS VMM040, many years ago.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- Linux/{m68k~Amiga,PPC~CHRP} -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds


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Re: RFC: Changing default partition type for linux/ppc

[Charles Stevenson]

I think it's a great idea. I don't use MacOS so I don't share the concern of
how MacOS X could affect the partitions. Equally, I trust if Apple is properly
advised of such a change they would take measures to ensure compatibility.
Linux sells Apple hardware too. ;-)

Best Regards,
Charles Stevenson

On Fri, 07 Jul 2000, Hollis Blanchard wrote:
> Tom Gall wrote:
> >
> > Benjamin Herrenschmidt wrote:
> > >
> > > So I suggest moving to Linux_ext2, Linux_swap, or maybe simply Linux and
> > > Linux_swap (since ext2 is not the only filesystem Linux may put on
> > > these). Using a different type for swap would help avoiding confusion.
> >
> > I agree. I think this is a good step. However there's the obvious interoperability
> > problems with MacOS, OS X etc... Hopefully Apple's OSes wouldn't do anything evil
> > to the partition they don't recognize.
>
> Well, they don't at this point. For example in partitioning tool in
> LinuxPPC 2000, LinuxPPC Inc decided it would be better to use the type
> "Linux_PPC". This works (in that nothing gets overwritten, corrupted,
> etc) but has the disadvantage that no other software knows anything
> about that type.
>
> If you were writing software it would be pretty poor form to find data
> you didn't understand and decide to "fix" it. I know there are programs
> like that out there (if you look at
> http://www.win.tue.nl/~aeb/partitions/partition_types-1.html it seems
> there is a rich history of them), but Apple seems to be doing well in
> that regard so far...
>
> Of course, everything may change with OS X but I would hope they don't
> get malicious all of a sudden.
>
> -Hollis
--
  Terra Soft Solutions, Inc.
  http://www.terrasoftsolutions.com/

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  http://www.yellowdoglinux.com/

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Re: RFC: Changing default partition type for linux/ppc

[Michael Schmitz]

> > > So I suggest moving to Linux_ext2, Linux_swap, or maybe simply Linux and
> > > Linux_swap (since ext2 is not the only filesystem Linux may put on
> > > these). Using a different type for swap would help avoiding confusion.
> >
> > I agree. I think this is a good step. However there's the obvious interoperability
> > problems with MacOS, OS X etc... Hopefully Apple's OSes wouldn't do anything evil
> > to the partition they don't recognize.
>
> Well, they don't at this point. For example in partitioning tool in
> LinuxPPC 2000, LinuxPPC Inc decided it would be better to use the type
> "Linux_PPC". This works (in that nothing gets overwritten, corrupted,
> etc) but has the disadvantage that no other software knows anything
> about that type.

So can we get all distributions to agree on this partition type scheme?
IIRC Debian currently relies on the Apple_Unix_SVR2 type, and ignores
everything else for the purpose of installing or creating swap space. I'd
like to update the Debian version of pdisk to recognize types used by
other distributions if possible.
LinuxPPC 1999 used the same type, and I think the 2000 change is a bad
thing. What are YellowDog and SuSE using?

Plus I don't think Apple cares too much, they may currently ignore strange
partition types but decide to nuke them tomorrow.

Benh: are you maintaining the official version of pdisk now?

	Michael


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Re: RFC: Changing default partition type for linux/ppc

[Mark Hatle]

That sounds like a great idea.  Looking at:
http://developer.apple.com/techpubs/mac/Devices/Devices-126.html

You'll see:
pmParType
              A string that identifies the partition type. Names that
begin with Apple_ are reserved for use by Apple Computer, Inc....

It looks to me that this allows us to use any name we wish, as long as
it doesn't start with "Apple_"

My vote: let the kernel still look for Apple_UNIX_SVR2 the way it does
now.  Then I would like it to be able to use anything that starts with
"Linux".  That way people can name there parts types whatever they want,
but Linux_ext2 and Linux_swap should be defaults.

Anyway, thats my suggestions, do what you wish!

Thanks!
--Mark


Benjamin Herrenschmidt wrote:
>
> Hi all !
>
> Currently, the default partition type used by Linux/PPC on mac partition
> maps is Apple_UNIX_SVR2. This is historically the type used by Apple's A/
> UX for its own partitions. However, I don't like it since it gives no
> indication on the type of filesystem on the partition, and I see no
> reason to keep it.
>
> So I suggest moving to Linux_ext2, Linux_swap, or maybe simply Linux and
> Linux_swap (since ext2 is not the only filesystem Linux may put on
> these). Using a different type for swap would help avoiding confusion.
>
> If everyone is ok, we can then update pdisk, and on my side, I'll update
> the kernel's root-auto-detect mecanism to take this into account. (The
> kernel will currently find by itself a root partition if it has the above
> type and the name "root" and no root= option was specified by the bootloader).
>
> Any comments ?
>
> Ben.
>

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Re: RFC: Changing default partition type for linux/ppc

[Nelson Abramson]

Benjamin Herrenschmidt wrote:

> >
> >Benh: are you maintaining the official version of pdisk now?
>
> No, I'm not. I don't know if someone actually maintains it

I believe one of the original (the original?) creator(s) of pdisk is now
part of the Linux/PPC community.  IIRC, he was working on upgrading pdisk
and fixing the problems that were highlighted previously in the list
archives.  I haven't heard anything recently, so I have no idea what the
status is.

--Nelson Abramson


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Re: RFC: Changing default partition type for linux/ppc

[Benjamin Herrenschmidt]

>
>Benh: are you maintaining the official version of pdisk now?

No, I'm not. I don't know if someone actually maintains it


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Re: RFC: Changing default partition type for linux/ppc

[Benjamin Herrenschmidt]

>with "Apple_"
>
>My vote: let the kernel still look for Apple_UNIX_SVR2 the way it does
>now.  Then I would like it to be able to use anything that starts with
>"Linux".  That way people can name there parts types whatever they want,
>but Linux_ext2 and Linux_swap should be defaults.

The kernel will be able to use anything. The only kernel change concerns
the root auto-detect stuff.

What will need to change, however, are the various distro installers,
pdisk, yaboot, perhaps quik, ...

Ben.

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Re: RFC: Changing default partition type for linux/ppc

[Ethan Benson]

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On Fri, Jul 07, 2000 at 06:14:09PM +0200, Michael Schmitz wrote:
> 
> So can we get all distributions to agree on this partition type scheme?
> IIRC Debian currently relies on the Apple_Unix_SVR2 type, and ignores
> everything else for the purpose of installing or creating swap space. I'd
> like to update the Debian version of pdisk to recognize types used by
> other distributions if possible.

this would certainly have to wait for woody... 

-- 
Ethan Benson
http://www.alaska.net/~erbenson/

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Re: RFC: Changing default partition type for linux/ppc

[Hollis Blanchard]

Michael Schmitz wrote:
>
> >
> > Well, they don't at this point. For example in partitioning tool in
> > LinuxPPC 2000, LinuxPPC Inc decided it would be better to use the type
> > "Linux_PPC". This works (in that nothing gets overwritten, corrupted,
> > etc) but has the disadvantage that no other software knows anything
> > about that type.
>
> So can we get all distributions to agree on this partition type scheme?
[snip]
> LinuxPPC 1999 used the same type, and I think the 2000 change is a bad
> thing. What are YellowDog and SuSE using?

I agree. So far the Linux "standard" has been to pretend to be A/UX
partitions. To my knowledge, every distribution with the exception of
LinuxPPC 2000 uses Apple_UNIX_SVR2. (And I'm not sure that alteration
was especially well thought out.)

> Benh: are you maintaining the official version of pdisk now?

That would be Eryk Vershen <eryk@cfcl.com>, who recently resurfaced in
February
(http://lists.linuxppc.org/listarcs/linuxppc-user/200002/msg01471.html).



So now that the conversation's died down, it seems like everybody's
happy with "Linux" (Mark Hatle's suggestion was for "Linux_*") and
"Linux_swap".

-Hollis

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Re: RFC: Changing default partition type for linux/ppc

[Tom Vier]

On Sat, Jul 08, 2000 at 12:21:37AM +0200, Benjamin Herrenschmidt wrote:
> >My vote: let the kernel still look for Apple_UNIX_SVR2 the way it does
> >now.  Then I would like it to be able to use anything that starts with
> >"Linux".  That way people can name there parts types whatever they want,
> >but Linux_ext2 and Linux_swap should be defaults.

> The kernel will be able to use anything. The only kernel change concerns
> the root auto-detect stuff.

> What will need to change, however, are the various distro installers,
> pdisk, yaboot, perhaps quik, ...

i'd vote for "ext2", "hfs", etc. call them what they are, and keep it simple,
instead of "Linux_Ext2fs" or something similar.

imho, partition types should be a "soft" standard. eg, an installer should
default to only showing Apple_UNIX_SVR2 (or whatever standard partition
names are created) unless the user selects "show all" or similar option.
this is somewhat offtopic, though.

--
Tom Vier <thomassr@erols.com>
DSA Key id 0x27371A2C

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Re: RFC: Changing default partition type for linux/ppc

[Benjamin Herrenschmidt]

>i'd vote for "ext2", "hfs", etc. call them what they are, and keep it simple,
>instead of "Linux_Ext2fs" or something similar.

That won't work for 2 reasons:

 - MacOS and MacOS X won't mount HFS partitions if the type is not Apple_HFS
 - If we put the fs type (like Linux_ext2) in the partition type, it's
not updated
   by the various linux mkxxxx tools, and can be confusing. I would
rather keep
   a simple "Linux" type, along with "Linux_swap" to help skipping swap
partition
   in bootloaders (and installers)

Ben.

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Re: RFC: Changing default partition type for linux/ppc

[Tom Vier]

On Sun, Jul 09, 2000 at 11:33:09PM +0200, Benjamin Herrenschmidt wrote:
> >i'd vote for "ext2", "hfs", etc. call them what they are, and keep it simple,
> >instead of "Linux_Ext2fs" or something similar.
>
> That won't work for 2 reasons:
>
>  - MacOS and MacOS X won't mount HFS partitions if the type is not Apple_HFS

you're right. i was just giving examples of names and hfs popped into my
head.

>  - If we put the fs type (like Linux_ext2) in the partition type, it's
> not updated
>    by the various linux mkxxxx tools, and can be confusing. I would
> rather keep
>    a simple "Linux" type, along with "Linux_swap" to help skipping swap
> partition
>    in bootloaders (and installers)

i'm not sure what you're saying. mkfs doesn't touch partition tables.

i was thinking of partition types as more of a description of the fs, rather
than naming them after the OS that uses them. on pcs, linux uses the same
partition type for all file systems (except for swap). it wouldn't be a bad
idea to do the same, as you seem to be saying. "Linux_swap" as a type does
seem a little redundant to me, since the partition name can be set to
"swap". on pc/dos style partitions they use a seperate type for for swap,
but they also don't have a seperate name field.

--
Tom Vier <thomassr@erols.com>
DSA Key id 0x27371A2C

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Re: RFC: Changing default partition type for linux/ppc

[Matt Brubeck]

On Sun, 9 Jul 2000, Tom Vier wrote:

>> If we put the fs type (like Linux_ext2) in the partition type, it's
>> not updated by the various linux mkxxxx tools, and can be confusing.
>> I would rather keep a simple "Linux" type, along with "Linux_swap" to
>> help skipping swap partition in bootloaders (and installers)

> i'm not sure what you're saying. mkfs doesn't touch partition tables.

That's the problem. If we create a partition with the label "ext2" and
later use mkfs to change the filesystem on that partition, the label stays
and is misleading.

Because people don't always change their partition tables when they switch
filesystems or operating systems, any label is liable to become
inconsistant with the actual disk state. Therefore, these type labels
should be used only as hints to bootloaders and installers and such; there
should always be a way to ignore them.


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Re: RFC: Changing default partition type for linux/ppc

[Michael Schmitz]

> > So can we get all distributions to agree on this partition type scheme?
> > IIRC Debian currently relies on the Apple_Unix_SVR2 type, and ignores
> > everything else for the purpose of installing or creating swap space. I'd
> > like to update the Debian version of pdisk to recognize types used by
> > other distributions if possible.
>
> this would certainly have to wait for woody...

Sure, but isn't woody right around the corner ?? :-)

Just wanted to make sure we get some sort of agreement.

	Michael


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