Dual issue means that each clock cycle the processor can move two instructions from one stage of the pipeline to the next stage. Where this happens depends on the processor and the company’s terminology: it can mean that two instructions are moved from a decode queue to a reordering queue (Intel calls this issue) or … Read more
You say “different than what we think of”, as if everyone thinks in the same way 🙂 I would guess that you are coming from low-end microcontrollers which often have separate program and data address spaces. On ARM the situation is different: program code, data and peripheral registers all reside in the same flat 32-bit … Read more
Just my 2 cents… I consult exclusively on embedded systems, most of them hard real-time and/or safety/life critical. Most of them run in 256K of flash/ROM or less – in other words, these are not “PC-like” VME bus systems with 1GB+ of RAM/flash and a 1GHz+ CPU. They are deeply embedded, somewhat resource-constrained systems. I … Read more
c++/cli can theoretically be used with WPF/Silverlight using the trick of replacing the C# generated from the XAML with a macro definition that can be used inside the main class in a code behind file. I worked out this technique but haven’t had the motivation to take it beyond theory – I’m quite happy mixing … Read more
In order to add your own machine, you need at least create one source file, containing the parameters and peripherals of your machine. After that, add a entry inside Makefile.objs, under qemu/hw/arm/. STM32 P103 machine entry. Let’s take as example Olimex STM32 P103 Development Board: Olimex STM32 P103 Development Board code. In lines 105 and … Read more
Sorry, not going to give you a straight-out example like you’re asking, because as you are already looking through the Linux source code, you have plenty of those to go around, and they don’t appear to help. No shame in that – every sane person is at least initially confused by memory access ordering issues … Read more
fixed, using: sudo apt-get install gcc-arm*
Regarding your general questions: Why the C library works: The C library is part of your cross toolchain. That’s why the headers are found and the program correctly links and runs. This is also true for some other very basic system libraries like libm and libstdc++ (not in every case, depends on the toolchain configuration). … Read more
It’s almost always returning from a function, like ret in some other ISAs like AArch64. bx stands for branch and exchange instruction set Which means that according to the lsb (least significant bit) of the address to branch to, the processor will treat the next instruction as ARM or as thumb. As lr usually holds … Read more
Some register calling conventions are dependent on the ABI (Application Binary Interface). The FP is required in the APCS standard and not in the newer AAPCS (2003). For the AAPCS (GCC 5.0+) the FP does not have to be used but certainly can be; debug info is annotated with stack and frame pointer use for … Read more