glibc 2.15 operates multiple allocation arenas. Each arena has its own lock. When a thread needs to allocate memory, malloc() picks an arena, locks it, and allocates memory from it. The mechanism for choosing an arena is somewhat elaborate and is aimed at reducing lock contention: /* arena_get() acquires an arena and locks the corresponding … Read more
It doesn’t need to call sqrt to compute the result; it’s already been calculated by the SQRTSD instruction. It calls sqrt to generate the required behaviour according to the standard when a negative number is passed to sqrt (for example, set errno and/or raise a floating-point exception). The PXOR, UCOMISD, and JBE instructions test whether … Read more
Using –platform is correct. On my M1 Mac I’m able to run both arm64 and amd64 versions of the Ubuntu image from Docker Hub. The machine hardware name provided by uname proves it. # docker run –rm -ti –platform linux/arm/v7 ubuntu:latest uname -m armv7l # docker run –rm -ti –platform linux/amd64 ubuntu:latest uname -m x86_64 … Read more
Here’s the complete table of registers and their use from the documentation [PDF Link]: r12, r13, r14, r15, rbx, rsp, rbp are the callee-saved registers – they have a “Yes” in the “Preserved across function calls” column.
These registers were originally implicitly used in repetitive instructions, for instance MOVSB, which copy a byte from DS:SI (DataSegment:SourceIndex) to ES:DI(ExtraSegment:DestinationIndex), at the time of the 16-bits computers with segmented memory in real mode. And also as index registers in 16-bit addressing modes like [bx + si]. Right now, these registers are for example used … Read more
So, unlikely as it may seem, we appear to have hit an actual bona-fide CPU bug. https://web.archive.org/web/20130228081435/http://support.amd.com/us/Processor_TechDocs/41322_10h_Rev_Gd.pdf has erratum #721: 721 Processor May Incorrectly Update Stack Pointer Description Under a highly specific and detailed set of internal timing conditions, the processor may incorrectly update the stack pointer after a long series of push and/or near-call … Read more
Hans and DarkDust answer covered i386/i686 and amd64/x86_64, so there’s no sense in revisiting them. This answer will focus on X32, and provide some info learned after a X32 port. x32 is an ABI for amd64/x86_64 CPUs using 32-bit integers, longs and pointers. The idea is to combine the smaller memory and cache footprint from … Read more
uname -m prints values such as x86_64, i686, arm, or aarch64.
First method – Easiest option- Check your Task Manager If you have Windows 10 or Windows 8 operating system, the easiest way to check is by opening up Task Manager->Performance Tab. You should see Virtualization as shown in the below screenshot. If it is enabled, it means that your CPU supports Virtualization and is currently … Read more
x64 is used as a short term for the 64 bit extensions of the “classical” x86 architecture; almost any “normal” PC produced in the last years have a processor based on such architecture. AMD invented the AMD64 extensions; Intel was more or less forced to implement them, and called them first IA-32e, then EM64T and … Read more