Differences between arm64 and aarch64

Question

I have two  unlocked  devices  an iPad mini 3  and a Galaxy Edge 6  both endowed with a terminal and a minimalistic set of unix commands  I thought both devices have arm64 processors but when I ran  uname -a   on both devices I got the following    for the iPad mini 3    xxxxs-iPad  var mobile root  uname -a Darwin xxxx-iPad 14 0 0 Darwin Kernel Version 14 0 0  Wed Jun 24 00 50 15 PDT 2015  root xnu-2784 30 7-30 RELEASE ARM64 S5L8960X iPad4    arm64    J85mAP   for the Samsung Galaxy s6 Edge    u0 a203 zerolte     uname -a Linux localhost 3 10 61-4497415  1 SMP PREEMPT Thu Apr 9 15 06 40 KST 2015   aarch64   GNU Linux   If I am not wrong  the last info in both case  J85mAP and GNU Linux  stand for firmwares  and the antepenultimate infos  arm64 and aarch64  stand for the processors   My questions are the following   obviously the strings  arm64  and  aarch64  are not the same  but I always thought arm64 and aarch64 were the same   It s even told when you put the arm64 tag to a question here      So  are they really identical     Especially  what should I worry about in case of cross-building libraries for both targets   In fact  I have gcc 5 2 0 in mind  but maybe also lower versions  Can I just pass  -target arm64   or  -target aarch64   according to which device I target and just worry about the rest of options to configure   EDIT Hum  look for this again  without success

User · Answer

It seems that ARM64 was created by Apple and AARCH64 by the others, most notably GNU/GCC guys.

After some googling I found this link:

The LLVM 64-bit ARM64/AArch64 Back-Ends Have Merged

So it makes sense, iPad calls itself ARM64, as Apple is using LLVM, and Edge uses AARCH64, as Android is using GNU GCC toolchain.

User · Answer

AArch64 is the 64-bit state introduced in the Armv8-A architecture  https   en wikipedia org wiki ARM architecture ARMv8-A   The 32-bit state which is backwards compatible with Armv7-A and previous 32-bit Arm architectures is referred to as AArch32  Therefore the GNU triplet for the 64-bit ISA is aarch64  The Linux kernel community chose to call their port of the kernel to this architecture arm64 rather than aarch64  so that s where some of the arm64 usage comes from   As far as I know the Apple backend for aarch64 was called arm64 whereas the LLVM community-developed backend was called aarch64  as it is the canonical name for the 64-bit ISA  and later the two were merged and the backend now is called aarch64   So AArch64 and ARM64 refer to the same thing

[android] Differences between arm64 and aarch64

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