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by DavidS
Fri Mar 15, 2019 10:55 am
Forum: Bare metal, Assembly language
Topic: Spider-OS a new operating system
Replies: 90
Views: 9369

Re: Spider-OS a new operating system

As it seems that you are intending to use a purely compositing window manager, I feel that I should point out that this makes for a very large use of memory. It may be a better bet to look at using a compositing window manager for the front most window and any that are flagged as compositing only (u...
by DavidS
Fri Mar 15, 2019 10:01 am
Forum: Bare metal, Assembly language
Topic: Puzzled, Mem speed?
Replies: 31
Views: 2317

Re: Puzzled, Mem speed?

You may want to look at STM timings even on an ARM7 and its similar on a cortexa53 https://hardwarebug.org/2014/05/15/cortex-a7-instruction-cycle-timings/ Thank you for that. That would infer that the STM/LDM ops are reading in 64-bit chunks on the ARMv7/8. Though testing would imply that they are ...
by DavidS
Fri Mar 15, 2019 9:56 am
Forum: Bare metal, Assembly language
Topic: Puzzled, Mem speed?
Replies: 31
Views: 2317

Re: Puzzled, Mem speed?

I am using the ARM STM instruction in a loop that I have verified to be the fastest possible, storing 4 registers per store (any more or less slows us down). Only one store per iteration of the loop (any more slows us down). I found that NEON had faster access to memory, I don't know why. NEON is q...
by DavidS
Fri Mar 15, 2019 8:18 am
Forum: Bare metal, Assembly language
Topic: Puzzled, Mem speed?
Replies: 31
Views: 2317

Puzzled, Mem speed?

If the SDRAM is clocked at 450MHz (RPi3B+) and the ARM external Data bus is 128 bits wide, I would expect the maximum throughput to be close to 6.86GB/s. From this we take off a little for refresh, so say 6GB/s. Even if we take off up to 1GB/s for the GPU to access RAM (more than twice the rate for ...
by DavidS
Tue Mar 05, 2019 4:53 pm
Forum: Off topic discussion
Topic: Is ARM doomed?
Replies: 311
Views: 18745

Re: Is ARM doomed?

Opcode fusion is certainly an idea around for RISC V. I have no idea if anyone has implemented such a thing yet. See here: https://www.youtube.com/watch?v=Ii_pEXKKYUg&t=56s Great presentation! Opcode fusion is an odd and new concept in my knowledge. It kind of seems like mixing some of what RISC is...
by DavidS
Tue Mar 05, 2019 4:44 pm
Forum: Bare metal, Assembly language
Topic: Spider-OS a new operating system
Replies: 90
Views: 9369

Re: Spider-OS a new operating system

I hope that good progress happens with Spider-OS. It also seems like he is getting some good baremetal resources together in one place, nice to see.
by DavidS
Tue Mar 05, 2019 4:42 pm
Forum: Bare metal, Assembly language
Topic: Spider-OS a new operating system
Replies: 90
Views: 9369

Re: Spider-OS a new operating system

LdB, The basic code for F(4784969) is simple enough I know, I put it there, it's my repo. Actually I would say that whilst the BASIC code is simple enough, it's just BASIC code after all, there is nothing simple about the whole thing. One has to know the algorithm for quickly calculating fibo() whi...
by DavidS
Tue Mar 05, 2019 4:32 pm
Forum: Other
Topic: Windows 10 ARM64 (Dekstop, not IOT)
Replies: 47
Views: 8878

Re: Windows 10 ARM64 (Dekstop, not IOT)

I will always point out that ReactOS is quite usable, it just has not got a working ARM native build yet, though the work is being done. So it makes more sense to help the ReactOS project get a working ARM native version with support for running on the RPi than to waste time attempting to get Win 1...
by DavidS
Tue Mar 05, 2019 4:21 pm
Forum: Other
Topic: Windows 10 ARM64 (Dekstop, not IOT)
Replies: 47
Views: 8878

Re: Windows 10 ARM64 (Dekstop, not IOT)

I've always found the builtin backup tools on windows to be poor, where they exist. CTRL C, CTRL V should be all you need, that or use the command line to clone a directory. Just... Don't copy a lot of files at once (size is of no concern, it's total file count that matters) as Windows tends to loc...
by DavidS
Mon Mar 04, 2019 10:56 pm
Forum: Off topic discussion
Topic: Is ARM doomed?
Replies: 311
Views: 18745

Re: Is ARM doomed?

Now look at that RISC V block diagram and imagine it supported DavidS' favored features: Addign it in to that single stage pipeline would be very inefecient. Though doable. User modifiable PC - We would need to add another pathway from the ALU and/or register file back into the PC selector multiple...
by DavidS
Mon Mar 04, 2019 8:28 pm
Forum: Off topic discussion
Topic: Is ARM doomed?
Replies: 311
Views: 18745

Re: Is ARM doomed?

DavidS, Your explanation is so complex that I'm really glad RISC V does not have a user modifiable PC, selectable setting of conditions or conditional execution :) At least from where I'm starting all of that would make even the simplest single stage RISC V more complex. This nice simple data path ...
by DavidS
Mon Mar 04, 2019 5:32 pm
Forum: Off topic discussion
Topic: Is ARM doomed?
Replies: 311
Views: 18745

Re: Is ARM doomed?

In what way can the ARM be better implemented? What techniques would that improvement use that cannot also be used in a RISC V design? Ok I will bite and answer. The techniques would be the same for both ISA's to reach ideal performance of the ISA. The difference is that a single instruction (howev...
by DavidS
Mon Mar 04, 2019 5:09 am
Forum: Off topic discussion
Topic: Is ARM doomed?
Replies: 311
Views: 18745

Re: Is ARM doomed?

All in all the ARM ISA is doomed, at least from ARM. The reason being that ARM is working hard at deprecating the ARM ISA, so the ARM we know and love will no longer be before long, at least it will no longer be licensed by ARM before long. Then the only ARM's will be those made by hobbyists and sma...
by DavidS
Mon Mar 04, 2019 3:58 am
Forum: Windows 10 for IoT
Topic: Can i run official 7" touch screen with raspberry pi 3 b+ on win 10 iot?
Replies: 17
Views: 1809

Re: Can i run official 7" touch screen with raspberry pi 3 b+ on win 10 iot?

Does the display work with Windows 10 IoT?

Is it that you are not getting any display, or that the touch input is non-functional?
by DavidS
Mon Mar 04, 2019 3:51 am
Forum: Windows 10 for IoT
Topic: Windows 10 IoT Core on Raspberry Pi 3 A+ does not boot?
Replies: 10
Views: 3238

Re: Windows 10 IoT Core on Raspberry Pi 3 A+ does not boot?

Windows 10 IoT lists the minimum memory requirements as 512MB available to the OS with video support. As videocore takes some RAM you will never have that much RAM available on the Raspberry Pi 3A+. At least 64MB goes to the VideoCore IV graphics processor, leaving 448MB or less for Windows 10 IoT, ...
by DavidS
Mon Mar 04, 2019 3:29 am
Forum: Other
Topic: RPI 3 A+ does not boot
Replies: 9
Views: 1873

Re: RPI 3 A+ does not boot

vcapeluto wrote:
Mon Mar 04, 2019 2:48 am
Hey guys,

I have installed Windows 10 IoT and Ubuntu Mate 16.04 and the Pi does not boot following all the instructions from the documentation, does anybody know if there's any trick on this or something?
How did you write the images to the SD Card?

Also have you tried Raspbian?
by DavidS
Mon Mar 04, 2019 1:36 am
Forum: General discussion
Topic: Zram and Swap Files
Replies: 20
Views: 10331

Re: Zram and Swap Files

Personally I just run with swap off, and take care to never hit the limit. I have noticed that whatever swapping algorithm is being used will cause swapping when one is only using a fraction of ram. For a while I was careful to keep memory usage under 256MB on the RPi 3B, and monitored swapping, it ...
by DavidS
Mon Mar 04, 2019 1:24 am
Forum: Raspbian
Topic: OpenSCAD
Replies: 12
Views: 816

Re: OpenSCAD

A quick read through Joel_Mckay's build instructions revealed that we both used Qt4 and 2GB swap files in order to build the binary. I've edited my earlier post to use qmake-qt4 rather than qmake. Although they're both the same on my installation, I imagine others might have qmake pointing to the Q...
by DavidS
Mon Mar 04, 2019 1:20 am
Forum: General discussion
Topic: Undervoltage even if there are no pheriphal plugged
Replies: 2
Views: 130

Re: Undervoltage even if there are no pheriphal plugged

Did you check the voltage at 5V and 3v3 test points on the board? If the voltage is high enough then it may be the firmware version, I had an issue like this with one version of the firmware, it was solved by updating the firmware.

BTW: My issue was on both the RPi 3B and RPi 3B+
by DavidS
Mon Mar 04, 2019 1:17 am
Forum: General discussion
Topic: Ideal temperatures.
Replies: 10
Views: 434

Re: Ideal temperatures.

The ideal temp is less than 85°C as that's the point when your RPi throttles back until the temp gets below that threshold. You only need to worry about cooling if you need high CPU speed & low temp. On a system that's always bottlenecked by slow I/O you're going to struggle to drive the CPU hard w...
by DavidS
Mon Mar 04, 2019 1:12 am
Forum: Bare metal, Assembly language
Topic: ARM processor stucks with "str" instruction while trying to access frame buffer address in Raspberry Pi 3
Replies: 5
Views: 1013

Re: ARM processor stucks with "str" instruction while trying to access frame buffer address in Raspberry Pi 3

Also you will need to put the unused cores to sleep in order to get the best performance, as they come up busy polling on a mailbox so taking a lot of bus time away from the core you are using. The other cores aren't exactly in a busy loop constantly polling, the loop has a WFE instruction in it wh...
by DavidS
Sun Mar 03, 2019 11:01 pm
Forum: Off topic discussion
Topic: Is ARM doomed?
Replies: 311
Views: 18745

Re: Is ARM doomed?

Soon after the introduction of the x86 based PC, IBM tried to make a System 370-compatible desktop computer. While that didn't result in a great success, it is not clear that Intel-compatible embedded designs are similarly doomed. From my point of view, the success of the AMD Ryzen Embedded V1000 a...
by DavidS
Sun Mar 03, 2019 8:45 pm
Forum: Other
Topic: Windows 10 ARM64 (Dekstop, not IOT)
Replies: 47
Views: 8878

Re: Windows 10 ARM64 (Dekstop, not IOT)

Can’t imagine why anyone would want to do this. Half the fun of Linux/Raspberry Pis is to escape the Windows oligarchy. (And I just bought a new Windows/Intel core i7 machine, so I’m not anti-windows) Now that I agree with. Windows has always been relatively little use compared to other systems. Ye...
by DavidS
Sun Mar 03, 2019 7:49 pm
Forum: Other
Topic: Windows 10 ARM64 (Dekstop, not IOT)
Replies: 47
Views: 8878

Re: Windows 10 ARM64 (Dekstop, not IOT)

Can it run modern programs/apps yet or is it stuck 6 to 10 years ago, or before that. preVISTA, Pre7? I can't see Windows8 mentioned on github readme. It's a great idea though. But doesn't really do what the intent is here. Yes it can run modern Win32 applications. It is only missing the ability to...
by DavidS
Sun Mar 03, 2019 7:42 pm
Forum: Off topic discussion
Topic: Is ARM doomed?
Replies: 311
Views: 18745

Re: Is ARM doomed?

At the end of the day any design is a mass of trade offs and compromises. ARM and RISC V guys have been thinking about all this, and actually implementing it, for a long time. They may have come to slightly different conclusions about which trade offs they think are best. At the end of the day the ...

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