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by bzt
Fri Feb 15, 2019 8:01 pm
Forum: Bare metal, Assembly language
Topic: Yet Another Bare Metal Tutorial for the RPi3
Replies: 59
Views: 32840

Re: Yet Another Bare Metal Tutorial for the RPi3

the LMA and VMA addresses look different, and the dwarf info unfortunately gets "corrupted" too (is different if embedded into a .text section). Most probably the corrupted debug-info from the .text section gets dumped into the baremetal image by "objdump -O binary ..." too (haven't tested though)....
by bzt
Fri Feb 15, 2019 3:09 pm
Forum: Bare metal, Assembly language
Topic: Spider-OS a new operating system
Replies: 63
Views: 2165

Re: Spider-OS a new operating system

I'm sure you will not say that calculating x^n or 2^n or doing that divide and multiply will take the same time no matter if n is ten, a hundred, a million, a billion, etc. Just because there is a "*" in the formula does not mean that multiply always takes the same time. Clearly it cannot as the op...
by bzt
Fri Feb 15, 2019 2:48 pm
Forum: Bare metal, Assembly language
Topic: Yet Another Bare Metal Tutorial for the RPi3
Replies: 59
Views: 32840

Re: Yet Another Bare Metal Tutorial for the RPi3

the dwarf info unfortunately gets "corrupted" I'm sorry, I can't give you cut out instructions here. The best advice I can give you is to try different configurations until the addresses in dwarf info became correct. Having debug info in the elf only and not in the img shouldn't be a problem, so in...
by bzt
Sat Feb 09, 2019 7:06 pm
Forum: Bare metal, Assembly language
Topic: Spider-OS a new operating system
Replies: 63
Views: 2165

Re: Spider-OS a new operating system

What an interesting conversation! :-) was able to remove one of the recursive calls. Which is pretty impressive, I gave you that. But still haven't changed the asymptotic behaviour. Clang compiles this entire function to one single instruction (on x86). Again, very impressive, non the less a special...
by bzt
Sat Feb 09, 2019 2:27 pm
Forum: Bare metal, Assembly language
Topic: RPi3 - start cores and spinlock sync code needed
Replies: 11
Views: 405

Re: RPi3 - start cores and spinlock sync code needed

PS: I am now writing a simple bootloader to avoid using the SD card Probably already written :-) Take a look at raspbootin and my 64 bit rewrite for booting over serial. Or you can boot from USB stick as well. and I wonder why the boot address changed from 0x8000 to 0x80000 when moving from Pi1 ro ...
by bzt
Sat Feb 09, 2019 1:28 pm
Forum: Bare metal, Assembly language
Topic: Spider-OS a new operating system
Replies: 63
Views: 2165

Re: Spider-OS a new operating system

Hi, I'm sorry I wasn't able to answer. You might be right. bzt's statement is somewhat ambiguous. At the same time it's "...use a different algorithm easily...", which is clearly easier to do in a high level language, and it's "...something a compiler optimizer will never ever able to do..." which i...
by bzt
Wed Feb 06, 2019 10:38 am
Forum: Networking and servers
Topic: Run script after network is online
Replies: 6
Views: 201

Re: Run script after network is online

Sorry if I've not been clear. I need internet connection to check for updates with rsync with my server. In that case running a script when your interface is up may not be the best solution, as there can be a lag between the interface is up, and internet is accessible. Getting an IP from a dhcp ser...
by bzt
Wed Feb 06, 2019 10:10 am
Forum: Networking and servers
Topic: Update variables in python script from web input
Replies: 4
Views: 107

Re: Update variables in python script from web input

Hi, update the values of variables in my python script with values coming from an input on the web page This is more problematic than you think. Keep in mind how web cgi works: 1. your browser asks for an URL 2. the webserver receives the request and sees that's a cgi 3. the webserver calls a python...
by bzt
Wed Feb 06, 2019 9:57 am
Forum: Bare metal, Assembly language
Topic: Yet Another Bare Metal Tutorial for the RPi3
Replies: 59
Views: 32840

Re: Yet Another Bare Metal Tutorial for the RPi3

...ruins this success by arbitrarily removing all debugging info This shouldn't be a problem. You run the .img, true, but you load the .elf (with all the sections) into gdb. Therefore gdb will be able to read the debug information and the symbols even though the running .img doesn't have them. But ...
by bzt
Tue Feb 05, 2019 12:09 pm
Forum: C/C++
Topic: Help with compiling source
Replies: 9
Views: 371

Re: Help with compiling source

Don't forget Qt comes from a time and a place where cmake did not exist and auto tools were not a thing. qmake was first ! Are you sure? The configure script first appeared in GNU in 1991. The first public realase of Qt was in 1995. Not that it matters. Sorry, we turned away a bit from the OP's ori...
by bzt
Tue Feb 05, 2019 11:45 am
Forum: Bare metal, Assembly language
Topic: Spider-OS a new operating system
Replies: 63
Views: 2165

Re: Spider-OS a new operating system

Hi, Then after different tests, it turned out that my code was not optimal in its processing, and then I used other specialized instructions, with a different algorithm. By checking the processing times of each code, we find the fastest solution. And that's the point. You, as a programmer can use a ...
by bzt
Mon Feb 04, 2019 11:43 am
Forum: Networking and servers
Topic: Security authentication compatible with REST API
Replies: 1
Views: 115

Re: Security authentication compatible with REST API

I don't know how to link the RFID with the user/password in the server Well, if there's only one RFID per user, you can add a new coloumn to the users table in your database. Otherwise I'd suggest to use a new rfiduser table. If you have an SQL database, that would be: SELECT users.* FROM rfiduser ...
by bzt
Mon Feb 04, 2019 11:16 am
Forum: C/C++
Topic: Help with compiling source
Replies: 9
Views: 371

Re: Help with compiling source

Are you saying you have built Qt apps using ./configure+make? I did not know this was possible and would love to hear how you do it. Sure, linking an application with Qt requires some C/C++ header files and a (shared) library. Configure (or any other build-system) can detect those, just like any ot...
by bzt
Mon Feb 04, 2019 12:40 am
Forum: Bare metal, Assembly language
Topic: Yet Another Bare Metal Tutorial for the RPi3
Replies: 59
Views: 32840

Re: Yet Another Bare Metal Tutorial for the RPi3

Being new to binutils and related tools, a quick bare-metal debugging-related question: how to modify the ‘link.ld’ script in bzt’s tutorials in order to contiguously include all debugging info (i.e. dwarf .debug_* sections) and how would e.g. a running program later discover its own debug info mem...
by bzt
Mon Feb 04, 2019 12:31 am
Forum: Bare metal, Assembly language
Topic: Spider-OS a new operating system
Replies: 63
Views: 2165

Re: Spider-OS a new operating system

While I definitely agree with bzt on point 1, on point 2 I am going to suggest that is very linux and single core centric answer. However it is not worth getting into until you start writing a multicore kernel and there are a number of elegant alternatives. Basically you will need your system call ...
by bzt
Mon Feb 04, 2019 12:13 am
Forum: C/C++
Topic: Help with compiling source
Replies: 9
Views: 371

Re: Help with compiling source

I'm worried this will not work on Raspbian. As far as I can tell the latest Qt for Raspbian is 5.7.1. This project requires new features in 5.8. There are two solutions to this. Neither very satisfactory ...and this is exactly why I consider qmake and similar build-systems a bad practice :-) Makefi...
by bzt
Sat Feb 02, 2019 12:51 pm
Forum: Networking and servers
Topic: Get me staight please!
Replies: 3
Views: 249

Re: Get me staight please!

A dynamic dns service like dyndns will enable you to consistently address your home network from the web externally without worrying about isp changes to your external ip. Or he could simply use a local WiFi connection. It is much simpler, much-much more secure. With that, he can also save a bookma...
by bzt
Sat Feb 02, 2019 12:41 pm
Forum: Bare metal, Assembly language
Topic: Spider-OS a new operating system
Replies: 63
Views: 2165

Re: Spider-OS a new operating system

Hi, Indeed before creating the elements that interact with the user as a web browser, you must already have the basic components of the system. I published an article about this, which lists all the essential basic modules : here . But it must be said that a calculator is a must have, which is easy ...
by bzt
Sat Feb 02, 2019 12:03 pm
Forum: C/C++
Topic: Help with compiling source
Replies: 9
Views: 371

Re: Help with compiling source

Hi, First, you'll need the libraries that your project depends on. There are usually two packages for each, a "libX" and a "libX-dev". First one required in run-time (contains the shared object binary), and the second one contains the C header files which you'll need for compilation. Then, you will ...
by bzt
Sat Jan 26, 2019 12:01 pm
Forum: Networking and servers
Topic: Remote tunneling certain port
Replies: 4
Views: 232

Re: Remote tunneling certain port

Hi, You can configure openvpn not to route all traffic into the tunnel, and I think this is your best chance. I don't think you can do what you want with a simple ssh port forward. The best would be to configure port forwarding and ip masquarading on your router, but if I'm right that belongs to you...
by bzt
Sat Jan 26, 2019 11:49 am
Forum: Bare metal, Assembly language
Topic: Spider-OS a new operating system
Replies: 63
Views: 2165

Re: Spider-OS a new operating system

Hi, First of all, sounds great! I really would like to see a demo and an online repo! it is true the assembly seems limited because it does not bring all the possibilities of a high level language like Python. But we know exactly the code that is generated. An assembly instruction is a code directly...
by bzt
Fri Jan 25, 2019 12:47 pm
Forum: General programming discussion
Topic: Creating a custom UI to boot up?
Replies: 5
Views: 286

Re: Creating a custom UI to boot up?

Hi, In regards to your questions, I would like to explore the possibility of having a GUI boot up when you power on the device. So when someone switches the device on, the GUI should be the main screen they see to switch between games. Oh, there are so many options for that. Here are some (ordered b...
by bzt
Fri Jan 25, 2019 12:15 pm
Forum: General programming discussion
Topic: Make a website on a server connect to a local Raspberry database
Replies: 2
Views: 195

Re: Make a website on a server connect to a local Raspberry database

Hi, Is it too complicated? And does anyone have an idea of how to implement it? Heater is right, allowing direct database access is a security nightmare. Instead I would create a minimal JSON RPC API on your server. Every time an RPi wants to write it's local database (insert/update/replace), I woul...
by bzt
Fri Jan 25, 2019 12:01 pm
Forum: General programming discussion
Topic: Start Python by PHP over Browser
Replies: 2
Views: 190

Re: Start Python by PHP over Browser

Hi, Now i need a way where i can execute a python-script by click a button/picture at the PHP-Website. ... The just thing i want to use i maybe the start.php who start the capture.py with admin-rights Steps: 1. create a link on the website to (let's say) start.php 2. in that start.php, call your pyt...
by bzt
Fri Jan 25, 2019 11:40 am
Forum: General programming discussion
Topic: Auto restart
Replies: 4
Views: 218

Re: Auto restart

Hi, Solution 1: You could create a small script on the RPi which runs with root privileges. That script would check the existance of a file, and could reboot. Something like: while [ ! -f $SEMFILE ]; do sleep 1; done rm -f $SEMFILE reboot Now with ftp or sftp you can upload that semaphore file as th...

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