This is a kernel source code question. If it isn't appropriate here, please let me know.
There's a macro called ipv4_is_loopback that would seem to be an appropriate way to determine if an address is a loopback or external. It has about 20 references in the kernel code I have seen. However, ifconfig (or ip) commands allow setting the address and mask for "lo". In testing, it seems that the setting via ifconfig seems to govern a lot of the behaviors - like transmitting a UDP packet. On the other hand, some of the kernel source code suggests that the macro may govern things like arp'ing. This seems strange.
Why are there two ways of determining if an address is a loopback?
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I'm working on a server whereas a fun thing for late December I want to make the whole world darker. The Minecraft sun usually has a light level of 15. Is there any way to lower the sun's light level to something like 8 so mobs can spawn on any block not under sunlight?
Any solution like datapacks, commands, or server plugins would work, but I wouldn't be able to use any mods (it could be super simple if I could use mods, but others would have to download it).
Thanks.
So I found this plugin online, which basically allows you to change light levels for things at will, and might solve your problem. If it doesn't, I also found this forum post, which may also help(but it is a bit more complex). It suggests decompiling Bukkit.jar(or whatever server software you use, Spigot, Paper, etc.), then editing the code for which mobs can spawn in.
I'd suggest looking into ProtocolLib plugin to send packets to players. I don't know which packet lighting would be in but if you use a tool called "pakkit" (https://github.com/Heath123/pakkit) you can watch Minecraft packets and that might help you see what causes light changes (example: place a torch in front of you and see what packet is sent). Then if you know what packets are sent you can modify packets as they are sent to include custom lighting data.
I want to develop a VGA graphics driver (for Linux(Ubuntu)) with support for the basic primitives such as putpixel, drawline, fillrect and bitblt. I want to do it in protected mode.
I´ve been googling for a week and the following four links are the best I have found:
http://www.brackeen....vga/basics.html
http://www.osdever.n...VGA/vga/vga.htm
http://bos.asmhacker...sing%20bios.htm
Unfortunately, the first one uses a BIOS call so I cannot use it. The second link has lots of information on the VGA registers but no examples showing how to make them work together. The third example is a example to switch in 13h mode but i've tried it and nothing happened. Can you guys give me a hint? Thanks in advance!
--Vincenzo
my code at http://bos.asmhackers.net/docs/vga_without_bios/snippet_5/vga.php
works fine if you are in 32bit mode with full hardware access. Unfortunately I doubt that any Linux variant will let you directly access the VGA ports. I'm not sure how you develop this driver, but if you made sure that you have full access to the VGA ports it should work. In my example code I only switch between mode 0x03 and 0x13, but in the folders above you'll be able to find port values for most other common VGA modes, as well as C code to do the switch if you prefer that.
Christoffer code include files are found BOS operating system source code like text.inc and font8x16.inc
http://bos.asmhackers.net/downloads.php
This is coming many many years later but I think it's still very relevant and if somebody is struggling I hope they can find it useful.
First of all, it is completely possible to configure VGA only using registers without interrupts, as hard as it may be. A useful resource about registers and how to configure them can be found here, but unless you have a ton of time to spare to learn how to properly do all of it, move to the following section.
If you wish to really learn how to do it, I suggest going through with the documentation provided earlier. However, some of it is already done!
Chris Giese did a great job demonstrating exactly how to do this for MS-DOS system, and while you may think that doesn't help you, it really does.
Chris's code can be found here. If you want another useful codes check here as well.
Now, while it only works for MS-DOS it's actually easy to convert to other systems. The code already contains all data needed to configure the registers in many different modes. And that's the part that saves you a ton of time going through documentation.
The code uses functions outportb, inportb, which are MS-DOS functions, to write/read single byte to/from a port. Therefore, you have to redefine these functions to read/write for your own system. Redefinition complexity depends on the system you operate on.
In addition, you will also need to provide means to write to physical memory region between 0xA0000-0xBFFFF which corresponds to standard VGA memory area. Once you have that allocated, you need to also redefine the functions pokeb pokew peekb which will help you output things (text or pixel data) on the screen.
One last note: the code is already defined to work with many different modes including both text and display modes.
So at work, we check computer's specifications, and need to print these in a standard format. I know how to set up a PXE server already, but I was wondering if it were easy to get a program (or write a script) that will check the computer's hardware (processor, memory, hard drive), and print it over the network.
My thoughts are that I can boot a very simple linux os over PXE, and run a script to do the dirty work. However, I'm not sure how to set it up to use a network printer, or which script to use for that matter.
All the computers have the same architecture, (x86), so a single implementation should work for all of them.
I would be inclined to avoid using a printer directly here and use something like scp or netcat to send back the information you discover.
Edit:
There are a number of tools that might help collecting the data itself, depending on what exactly you want to collect. I've found dmidecode to be very useful. Potientally it can tell you the version of the BIOS, memory stick size/speed/locations and quite a lot of very detailed information. It is buggy on some older hardware with broken DMI tables though. lshal, lshw, lspci and lsusb are all fairly common on linux installations and rather useful for these things.
Have a look at GLPI. It's a good open source software used to manage IT tickets, but, it also integrates a IT infrastructure management that could turn our to be useful in your case.
There is a small piece of software to be installed on each remote client (this could be done remotely and silently) and then you can collect a lot of information and match it by IP addresses
We use 'pdsh' to manage our global network. We have a naming convention of hosts that makes the host expression easy to write. So to continue the ls### suggestion to collect the info on a collection of hardware, we would write a command like this:
[root#admin-console ~]# pdsh -R exec -w china-[1-1024] ssh %h lshal > china-lshal-cabinet-01.log
pdsh prefixes the host name to the output lines and as it runs as a concurrent operator the lines will collate. A simple sorting script using the, say "china-[1-1024]:" tag is needed to get them organized. You could also make the pdsh run sequentially by limiting its concurrency but if you are running large configurations you would want the concurrency.
looking to bit-bang the I2C interface of a MCP23017 with an ATtiny13A, a lot of places mention HI2COUT as a method to send data on the I2C bus but i have no clue if this is part of a language or a Library or even a description of what happens when called. so the questions:
1) where can i get info on HI2COUT?
2) if any one has ever interfaces with an MCP23017 can you post the proper sequence to set 1 (or all) pins as output and set HIGH? (this includes start, write address, write register IOCON, ..., stop, etc...)
3) this may be to "Hardware" like for stackoverflow if anyone knows of a site better suited for this question (or may have the answer) please let me know.
Do you mean you're interested in programming the ATtiny13A (so that it can talk to a target device, which happens to be a MCP23017 but that's not an important detail)?
Just guessing, HI2COUT might be the name of a memory-mapped register to output data to the I2C peripheral of a microprocessor. However, looking at the ATtiny13A data sheet and the MCP23017 data sheet, I can't see such a register named. Perhaps that is the name of a register for an I2C peripheral of a different type of microprocessor?
The MCP23017 has I2C hardware built-in--see section 1.3.2 "I2C Interface" starting on page 5 of the MCP23017 data sheet. It will tell you how to do I2C on that device. But assuming it's the ATtiny13A you want to program, it looks as though it has no I2C hardware, so as you say, bit-banging is needed.
I suggest doing an Internet search for "ATtiny13A i2c" and you should be able to find several examples.
I want to work with a modem interfaced on a serial port on an embedded platform.
Here are some solutions I have rejected so far :
Expect plus a terminal program :
My (cross)build system does not have any package rules for expect, and according to the installation instructions from the expect sources, the configure script needs to be interactive because it does some test with the terminale it is invoked in. Thid does not look like something you want to do when cross compiling.
Python plus pyserial :
I would love to use this, but the size of the whole thing won't fit on my limited flash space.
Chat (from the pppd package):
Well, I may give it a try but it is very, very limited
So I am looking for some sort of lightweight, embeddable expect replacement. I have no knwoledge of lua. Would it be a good candidate for expect like scipting ?
Well, Expect is just Tcl plus extensions to drive other programs via pseudo-terminals and do pattern-matching on the results. If you just want to drive a serial port you can drop the external terminal program and have Tcl drive the serial port directly - see sample code. See also the Tcl Wiki page on cross-compiling.