Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.arch.embedded > #26759
| From | Don Y <blockedofcourse@foo.invalid> |
|---|---|
| Newsgroups | comp.arch.embedded |
| Subject | Re: ARM Cortex Mx vs the rest of the gang |
| Date | 2017-06-12 12:19 -0700 |
| Organization | A noiseless patient Spider |
| Message-ID | <ohmpac$usi$1@dont-email.me> (permalink) |
| References | (2 earlier) <4b6f7bfe-0a96-47eb-8530-e780f8d73b49@googlegroups.com> <8d5c9936-d0fd-4f7c-88d8-7dcd7c16c20b@googlegroups.com> <ohm9t1$gte$1@dont-email.me> <ohmho1$1u4$1@dont-email.me> <ohmofq$rke$1@dont-email.me> |
Hi Dimiter, On 6/12/2017 12:06 PM, Dimiter_Popoff wrote: > On 12.6.2017 г. 20:10, Don Y wrote: >>> .... >> >> Ideally, register-rich processors would implement a set of internal flags >> that would be set each time a register was loaded. And, a "save state" >> opcode that acted similar to the 09's PUSH "vector" saving only those >> registers that have been "altered". Then, letting the programmer >> clear this "flag register" as it reloaded the preserved state for >> the new task. > > I am not so sure how useful this would be, basically software knows > which registers have been used and which not, it is up to it to save > just what needs to be saved and restore it when needed only. You're not thinking with HLL's in mind -- where a *tool* creates the software (how does the tool tell you, concisely, which registers it used?) And, even if you know which registers were used, you don't know which were used SINCE THE LAST CONTEXT SWITCH! > It could be some help but not enough to justify the extra silicon & complexity > I believe. The silicon is trivial: each load of a register (or register in a register file) forces a corresponding bit to be set in a collection of flags. Then, a new "PUSH <vector>" opcode simply uses that "collection of flags" as the <vector>. If you had to "manually" examine the flags (bits) in that vector and conditionally save/restore registers, the overhead of doing so wouldn't offset the cost of just unconditionally performing the save/restore. In essence, this is what I do with my handling of the FPU context (see other post). I assume the FPU registers are NOT used and let the processor (in the NS32k example) tell me when a floating point instruction is invoked (the FPU is an optional component in the early NS32k systems; if it is NOT present, the opcodes are implemented by traps to user-supplied emulation functions) by invoking a TRAP handler. Of course, I can use that notification (with or without a hardware FPU) to alert the OS to the fact that the additional state is being referenced and save/restore it, as appropriate. [This only needs to happen at most once for each context switch]
Back to comp.arch.embedded | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
ARM Cortex Mx vs the rest of the gang Klaus Kragelund <klauskvik@hotmail.com> - 2017-05-30 05:11 -0700
ARM Cortex Mx vs the rest of the gang klaus.kragelund@gmail.com - 2017-05-30 05:48 -0700
Re: ARM Cortex Mx vs the rest of the gang Uwe Bonnes <bon@hertz.tu-darmstadt.de> - 2017-05-30 14:32 +0000
Re: ARM Cortex Mx vs the rest of the gang Tim Wescott <seemywebsite@myfooter.really> - 2017-05-30 22:07 -0500
Re: ARM Cortex Mx vs the rest of the gang rickman <gnuarm@gmail.com> - 2017-05-30 23:57 -0400
Re: ARM Cortex Mx vs the rest of the gang David Brown <david.brown@hesbynett.no> - 2017-05-31 12:08 +0200
Re: ARM Cortex Mx vs the rest of the gang rickman <gnuarm@gmail.com> - 2017-05-31 09:11 -0400
Re: ARM Cortex Mx vs the rest of the gang Tim Wescott <seemywebsite@myfooter.really> - 2017-06-01 15:17 -0500
Re: ARM Cortex Mx vs the rest of the gang rickman <gnuarm@gmail.com> - 2017-06-01 16:27 -0400
Re: ARM Cortex Mx vs the rest of the gang rickman <gnuarm@gmail.com> - 2017-06-01 16:30 -0400
Re: ARM Cortex Mx vs the rest of the gang Tim Wescott <seemywebsite@myfooter.really> - 2017-06-01 15:17 -0500
Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-05-30 07:31 -0700
Re: ARM Cortex Mx vs the rest of the gang Klaus Kragelund <klauskvik@hotmail.com> - 2017-05-30 08:07 -0700
Re: ARM Cortex Mx vs the rest of the gang George Neuner <gneuner2@comcast.net> - 2017-05-31 00:38 -0400
Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-05-30 22:14 -0700
Re: ARM Cortex Mx vs the rest of the gang rickman <gnuarm@gmail.com> - 2017-05-30 10:53 -0400
Re: ARM Cortex Mx vs the rest of the gang StateMachineCOM <statemachineguru@gmail.com> - 2017-06-07 12:58 -0700
Re: ARM Cortex Mx vs the rest of the gang Klaus Kragelund <klauskvik@hotmail.com> - 2017-06-07 13:27 -0700
Re: ARM Cortex Mx vs the rest of the gang Jack <jack4747@gmail.com> - 2017-06-07 23:24 -0700
Re: ARM Cortex Mx vs the rest of the gang StateMachineCOM <statemachineguru@gmail.com> - 2017-06-12 07:21 -0700
Re: ARM Cortex Mx vs the rest of the gang Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-12 17:57 +0300
Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-06-12 10:10 -0700
Re: ARM Cortex Mx vs the rest of the gang Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-12 22:06 +0300
Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-06-12 12:19 -0700
Re: ARM Cortex Mx vs the rest of the gang Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-12 23:04 +0300
Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-06-12 14:34 -0700
Re: ARM Cortex Mx vs the rest of the gang Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-13 02:44 +0300
Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-06-12 17:31 -0700
Re: ARM Cortex Mx vs the rest of the gang Jack <jack4747@gmail.com> - 2017-06-12 08:04 -0700
Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-06-12 09:54 -0700
Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-10 13:30 +0000
Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-07-10 16:03 -0700
Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-11 16:24 +0000
Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-07-11 12:15 -0700
Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-11 23:16 +0000
Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-07-12 11:44 -0700
Re: ARM Cortex Mx vs the rest of the gang George Neuner <gneuner2@comcast.net> - 2017-07-12 17:46 -0400
Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-07-12 18:12 -0700
Re: ARM Cortex Mx vs the rest of the gang Anders.Montonen@kapsi.spam.stop.fi.invalid - 2017-07-13 11:42 +0000
Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-07-13 21:38 -0700
Re: ARM Cortex Mx vs the rest of the gang David Brown <david.brown@hesbynett.no> - 2017-07-13 23:31 +0200
Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-14 15:27 +0000
Re: ARM Cortex Mx vs the rest of the gang David Brown <david.brown@hesbynett.no> - 2017-07-14 17:38 +0200
Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-14 16:03 +0000
Re: ARM Cortex Mx vs the rest of the gang David Brown <david.brown@hesbynett.no> - 2017-07-14 20:20 +0200
Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-14 18:59 +0000
Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-14 17:17 +0000
Re: ARM Cortex Mx vs the rest of the gang Dimiter_Popoff <dp@tgi-sci.com> - 2017-07-15 00:45 +0300
Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-14 23:00 +0000
Re: ARM Cortex Mx vs the rest of the gang Dimiter_Popoff <dp@tgi-sci.com> - 2017-07-15 04:04 +0300
Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-16 16:58 +0000
Re: ARM Cortex Mx vs the rest of the gang Richard Damon <Richard@Damon-Family.org> - 2017-07-14 20:05 -0400
Re: ARM Cortex Mx vs the rest of the gang Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-07-15 11:53 +0300
Re: ARM Cortex Mx vs the rest of the gang David Brown <david.brown@hesbynett.no> - 2017-07-15 12:05 +0200
Re: ARM Cortex Mx vs the rest of the gang Anders.Montonen@kapsi.spam.stop.fi.invalid - 2017-07-20 11:11 +0000
Re: ARM Cortex Mx vs the rest of the gang Anders.Montonen@kapsi.spam.stop.fi.invalid - 2017-07-20 10:29 +0000
Re: ARM Cortex Mx vs the rest of the gang "Boudewijn Dijkstra" <sp4mtr4p.boudewijn@indes.com> - 2017-06-14 09:54 +0200
csiph-web