Re: Minidisk support (was: Installation Question)
Stephen Powell wrote: OK, so if all three drivers support minidisks, then what is Debian bug report 447755 all about? The issue here is the *format* of the minidisk. A DASD device, be it a dedicated device or a minidisk, can have one of four formats under Linux for s390: cdl, ldl, CMS non-reserved, and CMS reserved. The FBA driver supports two of the four formats: CMS non-reserved and CMS reserved. The DIAG driver supports three of the four formats: ldl, CMS non-reserved, and CMS reserved. The ECKD driver supports all four formats. Debian installer includes 2 drivers: - dasd_fba_mod - dasd_eckd_mod The second one is the one that's normally loaded AFAIK, so that means all four formats should be supported. CMS non-reserved: Low-level formatting: CMS FORMAT command Partitioning: none (a single partition is implied) High-level formatting: mke2fs or mkswap CMS reserved: Low-level formatting: CMS FORMAT command Partitioning: CMS RESERVE command (a single partition is created) High-level formatting: mke2fs or mkswap Here's one of the reason why I cannot do anything about this: I only have access to Hercules running Linux, so I cannot create CMS formatted disks. The issue in 447755 is that the Debian installer only supports cdl format. Why? It has the eckd kernel driver which supports all four formats if I understand you correctly. The fact that you cannot do a low-level CMS format is IMO not relevant as the first thing should be to support pre-formatted disks anyway. High level formatting (partitioning and file system creation) is not an issue here. Once the basic device is recognized, that should be automatic (unless the device has a special naming convention that's not recognized by partman, but that is trivial to implement). The s390-dasd udeb takes care of identifying available channels. Are minidisks maybe not listed as ccw channels maybe, or are they of a special type? The s390-dasd C program is relatively simple: it's a state engine and all actual functionality is based in info from /sys/. So what exactly is missing there? At what point does it go wrong: is it in s390-dasd, or is it in partman? I still don't get it... And since this is the only format that the DIAG driver *doesn't* support, the DIAG driver cannot be used, even after installation, without migrating the data to other minidisks after the installation. The installer currently does not include the DIAG driver. I'm not sure why, but possibly to avoid having to choose between two different drivers supporting the same device. But if the ECKD driver really does support all formats, then shouldn't you be able to use that initially and then switch over to DIAG after the installation? If so, missing DIAG in the installer would be no huge issue. There is also another issue mentioned in 447755, and that is a problem with mounting devices in the wrong order. In hindsight, I should have created two separate bug reports: one for the lack of support for CMS minidisks and one for the mount order issue. You can still do that... I apologize for the long reply, but again; I don't know what you know and what you don't know. Well, the thing this has clarified most for me is that my original position is still correct: I cannot do anything about this as the problem is not clear. Especially without access to a CMS formatted minidisk I cannot even start to see what's missing. It also still seems to me that anybody who *does* have access to such devices should be able to implement basic support, even without much coding skills. And they could at least specify *in detail* what's missing by doing all the needed steps manually: - what kernel modules are involved? - what are the relevant files in /sys/ and what are their contents? - what must be done to activate a device? - does the kernel recognize the device (see dmesg)? - do device nodes get created for the device? - ... If a kernel module is missing, simply scp it from an installed system into the D-i environment, run 'depmod -a', modprobe it and it should work. Working on Debian Installer is not rocket science, really. As an official Debian developer, you carry more weight than I do. I can appeal to the kernel team, of course; but if you say I'm full of excrement, they'll believe you more than they will me. No really, I do not have *any* influence over this. Even the kernel team does not have that much influence over the release date. Things just slowly move towards the critical mass needed to release, and at that point only serious release critical issues can stop it. And this simply does not qualify. So what you should do is just work to get any pet issues fixed in time and not make a huge issue of things. That's exactly the same basis on which everybody works. There's *plenty* of time to get it done. You just have to make it happen. Cheers, FJP -- To UNSUBSCRIBE, email to debian-s390-requ...@lists.debian.org with a
Re: Minidisk support (was: Installation Question)
On 2009-12-24, Frans Pop wrote: Here's one of the reason why I cannot do anything about this: I only have access to Hercules running Linux, so I cannot create CMS formatted disks. Well, there are copies of very old releases of VM out there, such as VM/370 Release 6. VM/370 Release 6 has passed into the public domain now. But it is useless for this purpose. VM/370 Release 6 does not support the modern EDF disk format, with blocksizes of 512, 1024, 2048, and 4096. It only supports the original CDF format, with a blocksize of 800. That format is now obsolete, and Linux does not support it. It is technologically possible to run modern releases of z/VM under Hercules. I have heard that some people have done a Disaster Recovery Test of a modern z/VM system under Hercules. The problem is licensing. z/VM is not free software: you have to license it from IBM. And IBM normally won't license z/VM to run under Hercules, except maybe by special bid. And if they do license it to you by special bid, they'll probably charge you enough that it will be cheaper to buy a real mainframe and run it there! But I think IBM has, or used to have, some mainframes that have been set up for Linux developers to use, and they give away time and space on the machines for those who qualify. You might check into that. It would be nice if someone were to write a program that runs under Linux that can format a DASD device in the CMS format. That would help. As far as I know, there's no such program today. On 2009-12-24, Frans Pop wrote: Why? It has the eckd kernel driver which supports all four formats if I understand you correctly. The fact that you cannot do a low-level CMS format is IMO not relevant as the first thing should be to support pre-formatted disks anyway. Yes, that's true. I'm not asking for support for doing a low-level format in CMS format while the Debian installer is running. That would be wonderful, but even Suse doesn't give me that. All I'm asking for right now is the capability to use pre-formatted CMS disks. On 2009-12-24, Frans Pop wrote: So what exactly is missing there? At what point does it go wrong: is it in s390-dasd, or is it in partman? I still don't get it... I'm going from memory here. I haven't done an install in quite a while. But if I recall correctly, there is an initial screen in which the dasd devices that it finds are listed, and you can pick which ones you want to use. That works fine. Then there is a second screen after that on which you can do things like create partitions and assign mount points. I think that's partman. The problem is that a disk in CMS FORMAT, reserved or non-reserved, is treated like an unformatted disk. Partman does not recognize that the disk already has a partition on it. Therefore, I cannot assign a mount point to it or designate it as swap space. It will not let me do anything with the disk unless it runs dasdfmt and fdasd on it first. Then, and only then, does it recognize a partition on the disk, which I can assign a mount point to or designate as swap space. But that destroys the pre-existing CMS format which I need to keep. If I were to boil the problem definition down to one sentence it would be: Partman does not recognize the pre-existing partition on disks which are pre-formatted in the CMS non-reserved format or the CMS reserved format. It also still seems to me that anybody who *does* have access to such devices should be able to implement basic support, even without much coding skills. Well, I'm working on it, but I'm not there yet. I am currently teaching myself bash scripting by reading online tutorials and man pages. After that, I'll probably tackle awk, perl, and sed. And then eventually, C. I'm heading in the right direction. Maybe someday I'll be useful to you. But Rome wasn't built in a day. I'm sorry if the problem description wasn't clear to you. It was clear to me. But understanding a problem is one thing. Being able to explain it to someone else who comes from a different background and a different perspective is another thing. That takes work. And apparently I'm not as good at that as I thought I was. What I have is a real mainframe, a legitimate z/VM license, and a willingness to help. What I lack but am working on is Linux programming skills. I think I will eventually have them, but I'm not there yet. What I don't have, and likely never will, is FBA DASD. Someone else will need to test that support. You might be able to create emulated FBA dasd devices under Hercules. But formatting them in CMS format (EDF CMS format) is another story. In the meantime, if there's anything I *can* do for you, let me know. Merry Christmas! -- To UNSUBSCRIBE, email to debian-s390-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org
Re: Minidisk support (was: Installation Question)
Stephen Powell wrote: If I were to boil the problem definition down to one sentence it would be: Partman does not recognize the pre-existing partition on disks which are pre-formatted in the CMS non-reserved format or the CMS reserved format. Right. That narrows it down a lot. Partman is almost exclusively shell script, and is because of that relatively easy to play around with. Main problem is that it's a *HUGE* amount of shell script, so the main challenge is to find the correct place in the code. This should be fairly simple to solve. Well, I'm working on it, but I'm not there yet. I am currently teaching myself bash scripting by reading online tutorials and man pages. After that, I'll probably tackle awk, perl, and sed. For this issue shell scripting (plus basic sed, find, etc.) is all that's needed. What I have is a real mainframe, a legitimate z/VM license, and a willingness to help. If you can provide me with *exact* info I need and if you can reply quickly, I may be able to add support for this. If you could provide me with access to a system that has these disks mounted that might work as well. To start with: - What device name does such a partition have? - How could it be distinguished from a partitionable dasd? Please send the replies for these questions to the BR instead of the list! -- To UNSUBSCRIBE, email to debian-s390-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org
Re: Minidisk support (was: Installation Question)
On Thursday 24 December 2009, Frans Pop wrote: Stephen Powell wrote: Partman does not recognize the pre-existing partition on disks which are pre-formatted in the CMS non-reserved format or the CMS reserved format. Right. That narrows it down a lot. Partman is almost exclusively shell script, and is because of that relatively easy to play around with. Main problem is that it's a *HUGE* amount of shell script, so the main challenge is to find the correct place in the code. This should be fairly simple to solve. Hmmm. Possibly that info should come from libparted instead of partman itself. That would make it rather more difficult and probably beyond my skills. But we can give it a try. -- To UNSUBSCRIBE, email to debian-s390-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org
Re: Minidisk support (was: Installation Question)
On Thursday 24 December 2009, Frans Pop wrote: To start with: - What device name does such a partition have? - How could it be distinguished from a partitionable dasd? The output of the following command would be useful as well: # parted /dev/device print Please send the replies for these questions to the BR instead of the list! -- To UNSUBSCRIBE, email to debian-s390-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org
