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Re: Bug#569594: git t7400.24 is failing again

On Thu, 25 Mar 2010 13:09:19 -0400 (EDT), Jonathan Nieder wrote:
> Stephen Powell wrote:
>> If you're using Hercules, you have to define the the machine in Hercules
>> as a 64-bit machine, such as a z800, z900, etc.  A 64-bit kernel won't
>> run on an ESA/390 processor.
> Probably I misconfigured it.  With hercules 3.06-1.3, I tried
> "ARCHMODE z/Arch" in the configuration file;

I don't use hercules, but that sounds right.  Perhaps there are
other relevant settings too.  I don't know.  Someone who knows
Hercules please help out here.
> the lenny installer
> (which uses a 32-bit kernel) succeeded but the squeeze installer
> (which uses 64-bit) failed.

Hmm.  Well, I used a "daily-build" Squeeze/Sid installer for the s390
architecture a couple of months ago, which used a 2.6.30-2-s390x
kernel in the installer itself, if I'm not mistaken, and it worked
fine.  But then again, I ran it in a virtual machine under z/VM
running in an LPAR on a real mainframe, not under Hercules.
> From http://www.hercules-390.org/hercconf.html#ARCHMODE
> I see that the IPL always uses ESA/390 mode, so I can’t tell from the
> log whether this setting had the right effect.

An IPL includes an initial CPU reset, which does put the processor
into an ESA/390 compatibility mode at boot time.  But if you boot
a 64-bit kernel, the kernel will switch the processor to z/Architecture
mode very early on in the boot process via a SIGP order.  If this
order is issued on a z/Architecture-capable processor, the SIGP
order will work.  If this order is issued on a non-z/Architecture-
capable processor, the SIGP order fails, the kernel detects the
failure, and promptly commits suicide.  A 31-bit kernel never
attempts to issue that SIGP order and continues running happily
in ESA/390 compatibility mode.
> I’ll try spending more time to track it down with Hercules 3.07
> this weekend.  This time I can just install the new kernel on a
> working system to rule out other variables.

If your "working system" is on an ESA/390 processor, the 64-bit
kernel will die a spectacular death!  The processor must be
64-bit capable, even though it starts out in ESA/390 compatibility
mode at boot time, in order for that SIGP order to work.
>> I just realized that bug report #569594 is archived and has therefore
>> been silently rejecting all posts to it.
> Hmph.  Appears to be confused [1].  I’ve been receiving your messages
> through the Debian git packaging list, but the log as retrieved through
> http://bugs.debian.org and request@bugs.debian.org doesn’t include them.
> [1] http://thread.gmane.org/gmane.linux.debian.devel.bugs.rc/261981

That makes sense.  The bug tracking system continues to act as the
mail forwarding agent, but actual posts to the bug log are rejected.

  .''`.     Stephen Powell    <zlinuxman@wowway.com>
 : :'  :
 `. `'`

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