Linux on s/390 is cute
I took advantage of IBM's public mainframe system running Linux and compiled up a copy of BitKeeper on it. Didn't have to change a single line, just worked, thanks to gcc -Wall and friends.
This isn't a BK thing, it's a Linux thing. It's amazingly cool to me that Linux runs on stuff as small as all sorts of embedded devices, up to tiny PC's like a netwinder, all the way up to mainframes.
I'd really like to see the IBM guys let the walls between the linux instances down a bit. If I could mmap the other linux instances memory, that's a kickass system.
Anyway, kudos to the people who did the Linux/390 stuff, we'll include it in our list of supported platforms next release.
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--- Larry McVoy lm at bitmover.com http://www.bitmover.com/lm
Quoted 2 lines · Larry McVoy
I'd really like to see the IBM guys let the walls between the linux instances down a bit. If I could mmap the other linux instances
I guess the wall between the images is more an advantage than a disadvantage. And for sharing information between the images you have virtual network drivers IUCV (VM) or hypersockets(LPAR) with a theoretical bandwith up to 24Gbyte/sec for hypersockets.
That should be enough.....
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I took advantage of IBM's public mainframe system running Linux and compiled up a copy of BitKeeper on it. Didn't have to change a single line, just worked, thanks to gcc -Wall and friends.
BTW grab a copy of Hercules and you can test it at home. Its a very good S390 and ZSeries (S390 64bit) emulator..
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I'd really like to see the IBM guys let the walls between the linux instances down a bit. If I could mmap the other linux instances
I guess the wall between the images is more an advantage than a disadvantage. And for sharing information between the images you have virtual network drivers IUCV (VM) or hypersockets(LPAR) with a theoretical bandwith up to 24Gbyte/sec for hypersockets.
Some experimenting had been done with GFS across S/390 instances apparently
Quoted 3 lines · Larry McVoy
I'd really like to see the IBM guys let the walls between the linux instances down a bit. If I could mmap the other linux instances memory, that's a kickass system.
The situation is analagous to that of mapping memory between tasks in Linux. Instead of one task mapping another's address space directly, the usual design is to have both tasks do a shared mmap() of an underlying file. Similarly, with multiple Linux guests under VM, you can have them both map a shared pre-created Named Saved Segment (NSS).
Such an NSS is created by a guest with appropriate privileges via the CP command DEFSEG and then, once mapped and primed with its initial content, saved with SAVESEG. After that, other (permitted) guests can access and map it into their (perceived real) address space via the DIAGNOSE X'64' API. For details, see the manuals
"CP Command and Utility Reference" (SC24-6008-02) and
"CP Programming Services" (SC24-6001-01) available in PDF form from
http://www.vm.ibm.com/pubs/pdf/vm420bas.html
There's also DIAG X'248' ("Copy-to-Primary Service") which lets you copy memory from the address space of another guest into your own address space (obviously, the other guest must have set access controls to let you do it...). Nobody has yet published nice Linuxy interfaces to use either of these APIs but it's somewhere low down my ToDo list and I've a feeling someone else that's been looking at this stuff will probably beat me to it anyway.
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Anyway, kudos to the people who did the Linux/390 stuff, we'll include it in our list of supported platforms next release.
I'll check and see if it gets added to the Linux/390 software availability list.
--Malcolm
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Malcolm Beattie <[email protected]> Linux Technical Consultant IBM EMEA Enterprise Server Group... ...from home, speaking only for myself