wintermor.blogg.se - Diferenca entre x64 e x86

If you are looking for a test platform, then you can use Debian 8 or above.

be careful of the 0-extension that occurs on the upper 32-bits.

once a register is populated/configured from 32-bit data types, you can perform the 64-bit operations on them, like adcq.

when interacting with the stack, you must use the 64-bit instructions pushq and popq.

you cannot use _ILP32_ alone because it shows up unexpectedly under Clang and Sun Studio.

the preprocessor defines _x86_64_ (and friends) and _ILP32_, but not _i386_/ _i686_ (and friends).

Here is some of what I have learned through a recent port after the Debian folks reported a few bugs on us after testing: (Reference: Debian X32 Port page and X32 System V Application Binary Interface). When building a kernel, you must include the CONFIG_X86_X32=y option.

When booting a kernel with the support, you must use syscall.x32=y option. Kernel should limit stack and addresses returned from system calls between 0x00000000 to 0xffffffff. From the System V Application Binary Interface, AMD64 (With LP64 and ILP32 Programming Models), Section 10.4, p. Kernel support only required pointer to be in the range from 0x00000000 to 0xffffffff. It requires kernel support (3.4 and above), distro support (see below), libc support (2.11 or above), and GCC 4.8 and above (improved address size prefix support).įor distros, it was made available in Ubuntu 13.04 or Fedora 17.

netbooks/tablets (low memory, performance).

X32 can provide up to about 30% reduction in memory usage and up to about 40% increase in speed. The idea is to combine the smaller memory and cache footprint from 32-bit data types with the larger register set of x86_64.

X32 is an ABI for amd64/x86_64 CPUs using 32-bit integers, longs and pointers. This answer will focus on X32, and provide some info learned after a X32 port. Hans and DarkDust answer covered i386/i686 and amd64/x86_64, so there's no sense in revisiting them.