x86-64

Look at this code: one.cpp: bool test(int a, int b, int c, int d); int main() { volatile int va = 1; volatile int vb = 2; volatile int vc = 3; volatile int vd = 4; int a = va; int b = vb; int c = vc; int d = vd; int s = 0; __asm__("nop"); __asm__("nop"); __asm__("nop"); __asm__("nop"); __asm__("nop"); __asm__("nop"); __asm__("nop"); __asm__("nop"); __asm__("nop"); __asm__("nop"); __asm__("nop"); __asm__("nop"); __asm__("nop"); __asm__("nop"); __asm__("nop"); __asm__("nop"); for (int i=0; i<2000000000; i++) { s += test(a, b, c, d); } return s; } two.cpp: bool test(int a, int b, int c, int d) {

How are interrupts handled on SMP (Symmeteric multiprocessor/multicore) machines? Is there only one memory management unit or more? Say two threads, A and B running on different cores touch a memory page (at the same time) which is not there in the page table, in which case there will be a page fault and a new page is brought in from the memory. What is the sequence of events which will happen? If there is one memory management unit, to which core is the page fault forwarded to? How does the kernel handle it? Are there multiple instances of the kernel, each one running on a different core? If

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: The x86-64 instruction set adds more registers and other improvements to help streamline executable code. However, in many applications the increased pointer size is a burden. The extra, unused bytes in every pointer clog up the cache and might even overflow RAM. GCC, for example, builds with the -m32 flag, and I assume this is the reason. It's possible to load a 32-bit value and treat it as a pointer. This doesn't necessitate extra instructions, just load/compute the 32 bits and load from the resulting address. The trick won't be portable,

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: Intel i5-2410M CPU running at 2.30 GHz running a Windows 7 64-bit operating system. I have VirtualBox 4.13 installed. I am trying to run ubuntu-14.04-desktop-amd64.iso but I get an error this kernel requires an x86-64 cpu but only detected an i686 cpu I even enabled the Intel Virtualization in the BIOS settings and then tried to use the image again but I still get the same error. Is there any other reason why I can't use the image? 回答1: My best guess is that you somehow configured the VM for 32 bit execution instead of 64. Can you share the

I'm writing interrupt handling routines for x86_64. The ABI specifies that before calling a C function I must align the stack to 16 bytes. The x86_64 ISA specifies that on entry to an ISR, my stack is 8 byte aligned. I need to align my stack pointer to 16 bytes therefore. The issue is that on return from my C function, I must recover the (potentially) unaligned stack pointer so that I can return from my interrupt correctly. I wonder if there is a way to do this without using a general purpose register? Here's my solution to the question as put: pushq %rsp pushq (%rsp) andq $-0x10, %rsp call