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Re: Debian Version for System Z

On Wed, 11 May 2011 14:21:29 -0400 (EDT), Saulo Silva wrote:
> I would like to know about the current release of the Debian Linux for Z .
> And if that is a 64bit linux compile .

I'm not sure I understand your question.  Debian GNU/Linux has had an
s390 port since 3.0 (Woody).  Some other Linux distributions treat s390 and
s390x as separate architectures.  Debian does not.  Debian treats both ESA/390
processors and z/Architecture processors as belonging to the s390 architecture,
or "port".  Debian does provide two different flavors of kernel, however.
The s390 flavor runs on either an ESA/390 processor or a z/Architecture
processor.  The s390x flavor runs only on a z/Architecture processor.
Older releases of Debian provided only the s390 flavor.  For a while, a single
release of Debian provided both flavors, at the user's choice.  I'm not
sure which was the first release that provided the s390x flavor, but I do
know that Lenny (Debian 5.0) was the last release to provide the s390 flavor.
Starting with Squeeze (Debian 6.0), only s390x kernel flavors are provided.

The s390x flavor of kernel puts the processor into z/Architecture mode shortly
after IPL, and the processor stays in z/Architecture mode thereafter.  Debian
does not have a 64-bit user space, however.  The kernel (and it's modules)
run in 64-bit mode.  But user-space applications currently run in 31-bit mode.
Thus, a single user-space process is limited to 2G of (virtual) memory.
But the system can make use of more than 2G of real memory, since the kernel
can allocate (in theory) up to a 2G address space to EACH user-space process.


  .''`.     Stephen Powell    
 : :'  :
 `. `'`

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