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Re: ECMODE on in every user directory entry
On Sat, 30 Apr 2022 at 17:50, Dave Wade <dave.g4ugm@...> wrote:
Its a CP command. CP commands work with nothing IPL d in the VM. In fact if CMS is IPLdI was going to point that out. One may IPL CMS in a VM that’s going to run MVS or other OS so that you can tweak the configuration in ways that can’t be done in the directory. For example, an EXEC with the following commands:- &CONTROL OFF Will set ECMODE ON and then IPL from device 123.Isn't this where the (undocumented but everybody knows about it?) ability to put a X'15' byte in the command gets used? So you have a single command line with SET ECMODE ON;IPL 123 where the semi-colon is actually a X'15' (newline) byte. Or am I remembering a different context? Tony H. |
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Re: ECMODE on in every user directory entry
开云体育Hi, JUst for grins, I checked out both Bob Adele's 3 pack system that's on my system and the VM/370 R6 Sysgen manual.? They both show only 3 users with the ECMODE on the OPTION card in the User Directory.? MAINT, RSCS and a curious user called ECMODE. Regards, Gary On 4/30/22 18:29, Bob Polmanter wrote:
In most cases, there is no reason to specify ECMODE in each and every user directory entry.? IBM's own VM/370 documentation states this in so many words and also recommends against it for performance reasons.? A typical CMS user doesn't need ECMODE.? The user can do everything CMS supports: editing files, compiling, linking and executing user programs, use CMS and CP commands and more all without ECMODE. |
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Re: ECMODE on in every user directory entry
In most cases, there is no reason to specify ECMODE in each and every user directory entry.? IBM's own VM/370 documentation states this in so many words and also recommends against it for performance reasons.? A typical CMS user doesn't need ECMODE.? The user can do everything CMS supports: editing files, compiling, linking and executing user programs, use CMS and CP commands and more all without ECMODE.
ECMODE as implemented in VM/370 allows a given virtual machine these capabilities: - use of?virtual channels 6 through F - use of virtual control registers 1 through 15? (only CR 0 is available to a non-ECMODE virtual machine). - can use the DAT bit in the PSW - can turn on the EC bit in the PSW - can use PER bit in the PSW - can issue certain S/370 privileged instructions that would otherwise give an operation exception if issued in a non-ECMODE virtual machine. Unless you have user programming that does one or more of the items above, you do not need to run ECMODE.?? Normally, only guest operating systems would require ECMODE because they do do many of these items. Note that even if ECMODE is turned on but the PSW is in BC mode (bit 12 is zero), the virtual machine is still ECMODE capable; it is simply running in BC mode.? But not the reverse:? If ECMODE is not turned on and the PSW is in BC mode, you cannot enter EC mode by trying to set bit 12 of the PSW to 1. Regarding the performance cost of ECMODE, there are two factors.? The first is the additional real storage consumed so that CP can provide EC mode services to each virtual machine enabled for ECMODE.? This includes the ECBLOK, a system control block used to store the virtual control registers, as well as an increase in the size of the virtual channel block, virtual control unit blocks, and virtual device blocks as needed when the device addresses exceed 5FF.? For Hercules users, this is usually not a problem because we're all running with 16 MB of real memory, but if you can imagine a system from 1972 or 1974 with only 320K or maybe 448K of real memory and 30 or more VM users, a policy to give ECMODE capability to every user could be costly and exacerbate the paging rate. The other factor is the increase in the code path of CP in order to handle ECMODE virtual machines.? There is a lot of code in the system dispatcher that must validate certain bits in the PSW as well as bits and addresses in virtual control registers each time any user is dispatched and given control.? When ECMODE is enabled, CP must do a litany of additional checking.? Its not insignificant.? This does impact Hercules users too, because a longer code path in CP means more instructions must be executed (emulated).? Even ECPS is not immune.? In the Hercules code that provides ECPS support to CP, there are additional checks to determine if EC mode functions are enabled or used and if they are, Hercules ECPS support has to do more work to perform the given function.?? Granted that most of us would never notice the difference at the terminal whether ECMODE was enabled or not, but the above is what ECMODE provides, as well as an indication of what it costs. Regards, Bob |
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Re: ECMODE on in every user directory entry
开云体育Joe, Because that is what the manual says it does. Dave ? From: [email protected] <[email protected]> On Behalf Of Joe Monk
Sent: 30 April 2022 22:35 To: [email protected] Subject: Re: [h390-vm] ECMODE on in every user directory entry ? "Also note that what ECMODE ON does is to change the hardware being emulated by CP." ? how so? ? joe ? On Sat, Apr 30, 2022 at 2:32 PM Dave Wade <dave.g4ugm@...> wrote:
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Re: ECMODE on in every user directory entry
开云体育Joe, ? Its a CP command. CP commands work with nothing IPL d in the VM. In fact if CMS is IPLd and you do “SET MODE VM” you then need to re-ipl CMS because it resets the machine, as do some other CP commands ? However, its normal to have “OPTION ECMODE” on the directory for any VM that’s going to run MVS (or another OS that needs it). ? One may IPL CMS in a VM that’s going to run MVS or other OS so that you can tweak the configuration in ways that can’t be done in the directory. You do need to get creative, so if you issue a command that resets the machine, you need to have an IPL command on the console stack. ? For example, an EXEC with the following commands:- ? &CONTROL OFF &PUSH CP IPL 123 CP SET ECMODE ON ? Will set ECMODE ON and then IPL from device 123. ? Dave ? ? From: [email protected] <[email protected]> On Behalf Of Joe Monk
Sent: 30 April 2022 22:28 To: [email protected] Subject: Re: [h390-vm] ECMODE on in every user directory entry ? How would you issue CP SET ECMODE ON if MVS is the IPL'ed OS? CMS is never IPL'ed in the VM. ? Joe ? On Sat, Apr 30, 2022 at 2:02 PM Mark A. Stevens via <marXtevens=[email protected]> wrote:
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Re: ECMODE on in every user directory entry
"Also note that what ECMODE ON does is to change the hardware being emulated by CP." how so? joe On Sat, Apr 30, 2022 at 2:32 PM Dave Wade <dave.g4ugm@...> wrote:
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Re: ECMODE on in every user directory entry
On Sat, Apr 30, 2022 at 04:28 PM, Joe Monk wrote:
How would you issue CP SET ECMODE ON if MVS is the IPL'ed OS? CMS is never IPL'ed in the VM.In that particular case, you would have OPTION ECMODE in the directory entry for the userid that IPLs MVS. Dave's answer was what I needed. Sorry I wasn't clear. ?... Mark S. |
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Re: ECMODE on in every user directory entry
How would you issue CP SET ECMODE ON if MVS is the IPL'ed OS? CMS is never IPL'ed in the VM. Joe On Sat, Apr 30, 2022 at 2:02 PM Mark A. Stevens via <marXtevens=[email protected]> wrote: On Sat, Apr 30, 2022 at 01:36 PM, Joe Monk wrote: |
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Re: ECMODE on in every user directory entry
开云体育Mark, ? Historically the answer is “it depends”. The tendency was to leave ECMODE off because it can have a performance impact, so on a big system where you had lots of users, you left it off where possible. However, several products need to have ECMODE ON so you sometimes didn’t have any choice…. ? I suppose, simplistically with ECMODE OFF CP simulates a “360” except of course its not a 360 as there is no ASCII bit… When you SET ECMODE ON or have the OPTION ECMODE in the directory, which sets it on at logon, then roughly speaking CP simulates an S/370. Which is why you get a reset when changing the setting… It’s the classical function <=> performance trade-off. ? I also understand that the overhead depends on the processor. It may be that on machines with VMA or ECPS it may be less…. ? Also note that what ECMODE ON does is to change the hardware being emulated by CP. ?CMS itself will still only load BCMODE PSWs….. … Finally I would set ECMODE ON via an OPTIONS entry in the directory for IDs used by general users….. At some point in the future we will need it. ? Dave ? ? ? ? From: [email protected] <[email protected]> On Behalf Of Mark A. Stevens via groups.io
Sent: 30 April 2022 17:44 To: [email protected] Subject: Re: [h390-vm] ECMODE on in every user directory entry ? On Sat, Apr 30, 2022 at 09:44 AM, Mark Waterbury wrote:
So I am confused ... Surprise! It would seem "most" userids don't have the OPTION record, much less the ECMODE parm, but when it is specified, ECMODE is set ON at logon. Hence, if you need ECMODE on, it would be best to have it set in USER DIRECT?? ? |
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Re: ECMODE on in every user directory entry
On Sat, Apr 30, 2022 at 01:36 PM, Joe Monk wrote:
USER DIRECT is the user directory. You must have a user directory entry to have a VM. So, even VMs that run disconnected (like a VM running MVS or RSCS) have a user directory entry.Yes, Joe. But you missed the point. If you need ECMODE on, would it be best to have it set in USER DIRECT?? OR Is setting ECMODE ON (CP SET ECMODE ON), after logon, good enough?? Thanks! ?... Mark S. |
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Re: ECMODE on in every user directory entry
USER DIRECT is the user directory. You must have a user directory entry to have a VM. So, even VMs that run disconnected (like a VM running MVS or RSCS) have a user directory entry. Joe On Sat, Apr 30, 2022 at 11:44 AM Mark A. Stevens via <marXtevens=[email protected]> wrote: On Sat, Apr 30, 2022 at 09:44 AM, Mark Waterbury wrote: |
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Re: ECMODE on in every user directory entry
On Sat, Apr 30, 2022 at 09:44 AM, Mark Waterbury wrote:
True, but, CMS normally runs in BC mode.? Just saying ...So I am confused ... Surprise! It would seem "most" userids don't have the OPTION record, much less the ECMODE parm, but when it is specified, ECMODE is set ON at logon. Hence, if you need ECMODE on, it would be best to have it set in USER DIRECT?? Userid MAINT from USER DIRECT ... and no you can't know my password ;-) I have my own userid (XMAS) which mimics MAINT, and it behaves the same. FSVIEW: USER DIRECT A1?????????????? Lines 222-260/529 F80[1-79]? FSVIEW V1.2.5 USER MAINT *** 15M 16M ABCDEFGH??????????????????????????????????? 0215000 ?OPTION ECMODE LNKNOPAS???????????????????????????????????????????????? 0216000 ?IPL CMS??????????????????????????????????????????????????????????????? 0217000 ?CONSOLE 009 3215?????????????????????????????????????????????????????? 0218000 ?SPOOL 00C 2540 READ A????????????????????????????????????????????????? 0219000 ?SPOOL 00D 2540 PUNCH A???????????????????????????????????????????????? 0220000 ?SPOOL 00E 1403 A?????????????????????????????????????????????????????? 0221000 *??????? cuu type adr num volser mode readpw?? writepw? multpw????????? 0222000 ... FSVIEW: USER DIRECT A??????????????? Lines 500-529/529 F80[1-79]? FSVIEW V1.2.5 USER XMAS *** 15M 16M ABCDEFGH???????????????????????????????????? 0484010 ?OPTION ECMODE LNKNOPAS???????????????????????????????????????????????? 0484020 ?IPL CMS??????????????????????????????????????????????????????????????? 0484030 ?CONSOLE 009 3215?????????????????????????????????????????????????????? 0484040 ?SPOOL 00C 2540 READ A????????????????????????????????????????????????? 0484050 ?SPOOL 00D 2540 PUNCH A???????????????????????????????????????????????? 0484060 ?SPOOL 00E 1403 A?????????????????????????????????????????????????????? 0484070 ?LINK MAINT 190 190 RR????????????????????????????????????????????????? 0484080 ?LINK MAINT 19D 19D RR????????????????????????????????????????????????? 0484090 ?LINK MAINT 19E 19E RR????????????????????????????????????????????????? 0484100 ?LINK MAINT 5E5 5E5 RR????????????????????????????????????????????????? 0484110 *??????? cuu type adr num volser mode readpw?? writepw? multpw????????? 0484120 ... When I logon to MAINT, then ECMODE is ON. and it is not turned on by PROFILE EXEC, SYSPROF? EXEC, SYSPROFB EXEC, SYSPROFX EXEC. L MAINT ENTER PASSWORD: ? DASD 19D LINKED R/W; R/O BY 003 USERS DASD 19E LINKED R/W; R/O BY 005 USERS DASD 190 LINKED R/W; R/O BY 005 USERS DASD 5E5 LINKED R/W; R/O BY XMAS DASD 194 LINKED R/W; R/O BY CPWATCH LOGON AT 10:36:17 GMT SATURDAY 04/30/22 VM Community Edition V1 R1.1 ? Y (19E) R/O U (19D) R/O B (5E5) R/O Ready; T=0.01/0.01 10:36:21 q set MSG ON , WNG ON , EMSG TEXT, ACNT ON , RUN OFF LINEDIT ON , TIMER ON? , ISAM OFF, ECMODE ON ASSIST ON SVC?? TMR? , PAGEX OFF, AUTOPOLL OFF IMSG ON , SMSG OFF, AFFINITY NONE?? , NOTRANS OFF STBYPASS OFF Ready; T=0.01/0.01 10:36:24 ?... Mark S. |
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Re: ECMODE on in every user directory entry
开云体育Joe, ? I didn’t mention that because we were talking about “normal” CMS users, and normal CMS users don’t use DAT., but yes for many Operating Systems you need ECMODE. You, or “a n other” will now tell me that CMS must use DAT and I will say “no it doesn’t”. A CMS machine always runs with DAT off and usually runs with a virtual BC mode PSW so DAT is irrelevant for CMS. Of course CP uses DAT but all this is hidden from CMS running in its own little virtual padded cell. It knows nothing of such things. Whenever it looks at its PSW, it generates a privilege exception and CP fakes nice, safe BC Mode PSW for it. So yes, if you are going to load an OS into a VM that needs DAT you need ECMODE but that’s not something most users do… .. you may also ask “how does CMS do IO to the high channel numbers if its running with a BC Mode PSW, well CMS does not issue SIO’s for DASD it uses DIAGNOSE 18 which is a synchronous interface so none of that messy interrupt stuff and channel masking is required. ? Dave ? From: [email protected] <[email protected]> On Behalf Of Joe Monk
Sent: 30 April 2022 15:32 To: [email protected] Subject: Re: [h390-vm] ECMODE on in every user directory entry ? ECMODE is also required to use DAT. ? Joe ? On Sat, Apr 30, 2022 at 9:11 AM Harold Grovesteen <h.grovsteen@...> wrote:
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Re: ECMODE on in every user directory entry
CP SET ECMODE ON Joe On Sat, Apr 30, 2022 at 9:26 AM Dave Wade <dave.g4ugm@...> wrote:
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Re: ECMODE on in every user directory entry
ECMODE is also required to use DAT. Joe On Sat, Apr 30, 2022 at 9:11 AM Harold Grovesteen <h.grovsteen@...> wrote:
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Re: ECMODE on in every user directory entry
开云体育Harold, ? Its my experience that other things in VM required EC Mode because they also need like “SET TIMER REAL” which needs ECMODE and changing modes needs an IPL…. So for example many of the “WAIT” commands need ECMODE….. … so whilst running in BCMODE uses less resources, in many cases it creates problems so you set every one in EC MODE. If memory serves me correctly enabling ECMODE does NOT set the machine into ECMODE you need to load an ECMODE PSW….. ? Dave ? ? ? ? From: [email protected] <[email protected]> On Behalf Of Harold Grovesteen
Sent: 30 April 2022 15:11 To: [email protected] Subject: Re: [h390-vm] ECMODE on in every user directory entry ? I agree with the use of the I/O masks on S/360. ?However in BC-mode on S/370, bit 6 is architecturally available for enabling interrupts from higher channel numbers. ?GA22-7000-0, page 8. ?VM could have supported higher channel numbers in S/370 BC-mode. ?Whether any actual S/370 systems supported use of bit 6 in BC-mode could be a question. ?Clearly VM/370 does not implement use of bit 6 in BC-mode VM's. ?To the extent that VM virtual machines in BC mode were expected to support S/360 operating systems, it would make sense to only support PSW bits 0-5 for channel interruptions. ? Just a nit... ? Harold Grovesteen ? On Sat, 2022-04-30 at 08:24 -0500, Jay Maynard wrote:
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Re: ECMODE on in every user directory entry
开云体育I agree with the use of the I/O masks on S/360. ?However in BC-mode on S/370, bit 6 is architecturally available for enabling interrupts from higher channel numbers. ?GA22-7000-0, page 8. ?VM could have supported higher channel numbers in S/370 BC-mode. ?Whether any actual S/370 systems supported use of bit 6 in BC-mode could be a question. ?Clearly VM/370 does not implement use of bit 6 in BC-mode VM's. ?To the extent that VM virtual machines in BC mode were expected to support S/360 operating systems, it would make sense to only support PSW bits 0-5 for channel interruptions. Just a nit... Harold Grovesteen On Sat, 2022-04-30 at 08:24 -0500, Jay Maynard wrote:
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Re: ECMODE on in every user directory entry
It's an architecture limitation. The original 360 architecture allocated one bit in the PSW for each channel's interrupt status, and that's the PSW you get in BCMODE. If you want more than 6 channels, you need to be in ECMODE so you can get interrupts for the ones higher than 5. On Sat, Apr 30, 2022 at 8:21 AM Harold Grovesteen <h.grovsteen@...> wrote:
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Jay Maynard |
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Re: ECMODE on in every user directory entry
开云体育Can you describe why this is so? ? Is it a VM limitation or an architecture limitation? Harold Grovesteen On Fri, 2022-04-29 at 19:49 +0000, Walter Eggmo via groups.io wrote: ECMODE is required to access the higher channel numbers.? |
Mark A. Stevens