Re: diagnose 8 / interesting dilemma
Thank you for all of the responses and ideas. I guess if your 'guest operating system' is something like 'CMS' then it is quite easy to get consecutive pages of real storage addresses. But not quite so easy with z/os. I guess if you really want to do 'query virtual dasd' under z/os pre z/vm 6.4 you would need to do it via multiple calls to diagnose 8 and doing a 'query virtual -' into the 4k buffer and then further parse out the DASD addresses. Or use Ed Jaffe's methodology. Thank you. Paul -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: diagnose 8 / interesting dilemma
> What happens if AMODE 31 code issues LRA and the real address > is above the bar? Program check? yes. The ramifications of using the mod-2G part of the real address were quite obvious. The architecture reflected that understanding by making this case program check. >Or does LRA simply (always?) load a 64-bit register? no >Is there an LRAG instruction? yes Peter Relson z/OS Core Technology Design -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: diagnose 8 / interesting dilemma
On 18 October 2016 at 13:15, Paul Gilmartin <000433f07816-dmarc-requ...@listserv.ua.edu> wrote: > I find: > z/OS 2.2.0 > z/OS MVS > z/OS MVS Programming: Assembler Services Guide > Understanding 31-bit addressing > Understanding the use of central storage > Central storage considerations for user programs > Load real address (LRA) instruction As suggested, you need to look at the Principles of Operation. LRA is a matter of hardware, not MVS. Of course the MVS environment potentially affects some things, but LRA is entirely defined by the hardware. > Woe be unto anyone who did LRA; LA in AMODE 24 (But why?. And it > doesn't discuss AR mode. Perhaps elsewhere, but my curiosity is exhausted. POO. > Which leaves a historical question. Was AMODE 31 antedated by the > availability of real storage >16 MiB, Assuming you mean the hardware addressing mode, rather than the MVS Assembler and Binder's notion of AMODE for modules, Yes. But in a quirky way. In the pre-XA era, there was a time when 64 MB of real storage could be addressed by DAT tables, but not by channels or instructions running with DAT off. > or was AMODE 64 antedated by the availability of real storage >2GiB? How is this an "or"? You sound like a lawyer at bar: "My client did not kill Mr X, or in the alternative, if he did kill Mr X he did it with justification." Maybe I just need to apply De Morgan to your sentence... > How did LRA(G) operate in those eras? LRA provided a 26-bit real address (padded on the left to 32 bits) in the 64 MiB era. > And in a virtual guest with shadow page tables, does LRA return the > real real address or a virtual real address? Always a virtual real address. > I suppose it's all emulated by CP anyway, so it depends. No, it doesn't depend. What sense would it make to return a real real address to LRA? If you want a real real address you need to use a conceptually different level of query; a meta-query, one might say. Normally this would be a Diagnose. > Or maybe SIE. My head hurts. With (XA+) or without (370 pre-XA) SIE, the result is the same. With SIE it's all handled by the "hardware". Pre SIE, since LRA is privileged, and the guest always runs in real problem state, CP provides the answer. Tony H. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: diagnose 8 / interesting dilemma
On Mon, 17 Oct 2016 10:08:50 -0700, Ed Jaffe wrote: >> >> Hmmm... What happens if AMODE 31 code issues LRA and the real address >> is above the bar? Program check? Or does LRA simply (always?) load a >> 64-bit register? Is there an LRAG instruction? > >Why not take at least a cursory glance at Principles of Operation before >asking such questions publicly? > You're right; thanks. GIMF. (Oops; the Urban Dictionary says that doesn't mean what I expected.) I find: z/OS 2.2.0 z/OS MVS z/OS MVS Programming: Assembler Services Guide Understanding 31-bit addressing Understanding the use of central storage Central storage considerations for user programs Load real address (LRA) instruction Woe be unto anyone who did LRA; LA in AMODE 24 (But why?. And it doesn't discuss AR mode. Perhaps elsewhere, but my curiosity is exhausted. Which leaves a historical question. Was AMODE 31 antedated by the availability of real storage >16 MiB, or was AMODE 64 antedated by the availability of real storage >2GiB? How did LRA(G) operate in those eras? And in a virtual guest with shadow page tables, does LRA return the real real address or a virtual real address? I suppose it's all emulated by CP anyway, so it depends. Or maybe SIE. My head hurts. Thanks, gil -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: diagnose 8 / interesting dilemma
> Of course there's the question of whether z/VM yet supports the large > pages (EDAT-1) needed to make this work. I don't believe it does as of > 6.3, though I may have missed an announcement. Good point, and the second time in a month that I have embarassingly forgotten about that (Peter Relson will remember the first time). z/VM 6.4 will support 1MB pages for guests. http://www-01.ibm.com/common/ssi/ShowDoc.wss?docURL=/common/ssi/rep_ca/9/897/ENUS216-009/index.html&lang=en&request_locale=en Jim Mulder z/OS Diagnosis, Design, Development, Test IBM Corp. Poughkeepsie NY -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: diagnose 8 / interesting dilemma
On 17 October 2016 at 13:47, Jim Mulder wrote: > There is IARV64 GETSTOR with TYPE=FIXED and PAGEFRAMESIZE=1M. It's perhaps not 100% clear how it uses the 64-bit registers, but z/VM does seem to support AMODE 64 for the caller of Diagnose 8, so I think this could work. I suppose these days a megabyte of fixed storage here or there doesn't count for much. Of course there's the question of whether z/VM yet supports the large pages (EDAT-1) needed to make this work. I don't believe it does as of 6.3, though I may have missed an announcement. Tony H. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: diagnose 8 / interesting dilemma
>>> On 10/17/2016 at 02:23 AM, Paul Schuster wrote: > I am issuing DIAGNOSE 8 on my z/os image under VM (z/vm) to do a QUERY > VIRTUAL DASD. It works*up to a certain point: > > The QUERY VIRTUAL DASD command returns (for me) 38617 (decimal) bytes, > according to the CC=0 after the DIAGNOSE 8 command. My buffer is large > enough to accommodate this. I have tried several different sub-pools of > storage. I PGSER FIX the buffer pages. I do a SYSEVENT DONTSWAP. I do a > LRA of the virtual address of the start of the buffer. The DIAGNOSE > completes CC=0. But, in my buffer, I am only seeing the first page (4095) > bytes of the output. > > My question: I don*t see any documented restriction in the VM manuals that > limits the DIAGNOSE 8 output buffer to 4K (rather the limitation is the > architecture limit depending on your amode.) The z/vm manuals say the buffer > can cross page boundaries. So is there a way to force the real storage > addresses of the page-fixed pages to be consecutive? According to the > diagnose 8 doc., the buffer needs to be in guest-real storage, hence the LRA. > And it is working for the first 4k page. > > Thank you for any insight you can provide. I have no idea how well the concepts will transfer, but Linux has had a command that issues DIAGNOSE 8 calls for a very long time now. That command was originally "hcp" by Neale Ferguson, but then IBM created a different version called "vmcp". Those commands work, so you might be able to figure out what they're doing and apply that to your program. Mark Post -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: diagnose 8 / interesting dilemma
> I am issuing DIAGNOSE 8 on my z/os image under VM (z/vm) to do a > QUERY VIRTUAL DASD. It works?up to a certain point: > > The QUERY VIRTUAL DASD command returns (for me) 38617 (decimal) > bytes, according to the CC=0 after the DIAGNOSE 8 command. My > buffer is large enough to accommodate this. I have tried several > different sub-pools of storage. I PGSER FIX the buffer pages. I do > a SYSEVENT DONTSWAP. I do a LRA of the virtual address of the start > of the buffer. The DIAGNOSE completes CC=0. But, in my buffer, I am > only seeing the first page (4095) bytes of the output. > > My question: I don?t see any documented restriction in the VM > manuals that limits the DIAGNOSE 8 output buffer to 4K (rather the > limitation is the architecture limit depending on your amode.) The > z/vm manuals say the buffer can cross page boundaries. So is there > a way to force the real storage addresses of the page-fixed pages to > be consecutive? According to the diagnose 8 doc., the buffer needs > to be in guest-real storage, hence the LRA. And it is working for > the first 4k page. RSM internally manages double frames (used for access lists, and before z/Architecture, for segment tables) and quadframes (used for segment tables and region tables). There are no external interfaces for double frames or quadframes. There is IARV64 GETSTOR with TYPE=FIXED and PAGEFRAMESIZE=1M. Jim Mulder z/OS Diagnosis, Design, Development, Test IBM Corp. Poughkeepsie NY -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: diagnose 8 / interesting dilemma
On 10/17/2016 9:16 AM, Paul Gilmartin wrote: Hmmm... What happens if AMODE 31 code issues LRA and the real address is above the bar? Program check? Or does LRA simply (always?) load a 64-bit register? Is there an LRAG instruction? Why not take at least a cursory glance at Principles of Operation before asking such questions publicly? -- Edward E Jaffe Phoenix Software International, Inc 831 Parkview Drive North El Segundo, CA 90245 http://www.phoenixsoftware.com/ -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: diagnose 8 / interesting dilemma
On Mon, 17 Oct 2016 12:12:38 +0200, Christian Borntraeger wrote: > >As you already guessed, the memory you get is virtual, so the pages are not >consecutive. The LRA will give you the address of the first page, but the 2nd, >3rd and so on will be somewhere else. Please note that your code will even >cause random memory overwrites in your z/OS as the diag8 will write to the >real address of your LRA, the real address of your LRA+4096 and so on. > Ouch! But can't physical pages nowadays be much larger than 4096 bytes? Might the real address be above the bar? Does DIAG 8 support buffers above the bar? Otherwise it would be prudent design for DIAG 8 to reject requests when the reply buffer might cross physical page boundaries? Do some OSes support allocation of contiguous pages? I suppose V=R is obsolete nowadays. Hmmm... What happens if AMODE 31 code issues LRA and the real address is above the bar? Program check? Or does LRA simply (always?) load a 64-bit register? Is there an LRAG instruction? -- gil -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: diagnose 8 / interesting dilemma
On 10/17/2016 08:23 AM, Paul Schuster wrote: > I am issuing DIAGNOSE 8 on my z/os image under VM (z/vm) to do a QUERY > VIRTUAL DASD. It works—up to a certain point: > > The QUERY VIRTUAL DASD command returns (for me) 38617 (decimal) bytes, > according to the CC=0 after the DIAGNOSE 8 command. My buffer is large > enough to accommodate this. I have tried several different sub-pools of > storage. I PGSER FIX the buffer pages. I do a SYSEVENT DONTSWAP. I do a > LRA of the virtual address of the start of the buffer. The DIAGNOSE > completes CC=0. But, in my buffer, I am only seeing the first page (4095) > bytes of the output. > > My question: I don’t see any documented restriction in the VM manuals that > limits the DIAGNOSE 8 output buffer to 4K (rather the limitation is the > architecture limit depending on your amode.) The z/vm manuals say the buffer > can cross page boundaries. So is there a way to force the real storage > addresses of the page-fixed pages to be consecutive? According to the > diagnose 8 doc., the buffer needs to be in guest-real storage, hence the LRA. > And it is working for the first 4k page. > > Thank you for any insight you can provide. As you already guessed, the memory you get is virtual, so the pages are not consecutive. The LRA will give you the address of the first page, but the 2nd, 3rd and so on will be somewhere else. Please note that your code will even cause random memory overwrites in your z/OS as the diag8 will write to the real address of your LRA, the real address of your LRA+4096 and so on. I do not know if there is an interface to get consective real memory as I am not an Z/OS expert. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
