From 3b969f672c938142f0f2225ae2ffc153dfa19494 Mon Sep 17 00:00:00 2001 From: Zach Oglesby Date: Aug 22 2013 13:02:25 +0000 Subject: Started work on Introduction section --- diff --git a/en-US/Introduction.xml b/en-US/Introduction.xml index 08386a9..a5a6398 100644 --- a/en-US/Introduction.xml +++ b/en-US/Introduction.xml @@ -6,6 +6,66 @@ ]>
- Introduction to ARM - +
+ Introduction to ARM + + ARM chips are the most widely-produced processor family in the world; they have historically been used in cell phones and embedded applications, but were originally designed as desktop processors, and are increasingly used in tablet devices and low-power-consumption servers. + + + The Fedora-ARM project is an initiative to bring Fedora to this processor family. + +
+ Why ARM? + + + Low Power Consumption / Better efficiencies + + + High levels of device integration -- "system on a chip" designs, with reduced space and cooling requirements + + Readily available from multiple vendors + + + Low cost + + +
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+ Why does Fedora care about ARM? + + + Emerging technology (as a general purpose computing platform) + + + Growing user base + + +
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+ Understanding ARM +
+ Software floating point vs. Hardware floating point + + Fedora currently offers two flavours of ARM - 'arm(sfp)' and 'armhfp'. This is a reference to whether floating point values are passed to functions via CPU registers (sfp) or FPU registers (hfp); note that both API variants can use the FPU to perform arithmetic. + + + Here is the background: In older ARM chips (prior to ARM v7 "Application Profile"), the floating point unit (FPU, typically a vector floating point unit or "VFP") was optional. Therefore, function arguments were passed in the CPU registers or on the stack. However, when an FPU is available, moving floating-point values from the CPU registers to the FPU registers and back again has a significant cost which negates some of the advantage of having the additional arithmetic hardware. When the FPU became mandatory with ARMv7, it made sense to pass floating-point arguments directly in FPU registers. This is an incompatible ABI change, so programs which pass value in the CPU registers are incompatible with libraries that pass values in the FPU registers (and vice versa). + +
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+ Currently-Supported ARM Architectures + + + armv7hl - 32-bit, little-endian, hfp for ARM v7 processors. Supported from F15 onwards. + + + armv5tel - 32-bit, little-endian, sfp for ARM v5 to v7 processors. Supported until F18 (including F18 updates). + + + Community builds: Seneca is building for the armv6hl architecture specifically for the Raspberry Pi, more imformation on this effort can be found at + + +
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