This post is about i386 / x86_32. What you're referring to is "x32," a different thing entirely, which uses the x86-64 instruction set. You can tell this post is not about "x32" because it talks about "segments, gates, and other delights from the i386 era," which don't exist on the x86-64 architecture regardless of how long your pointers are, and it says things are "fine on a 64-bit kernel" (x32 uses a 64-bit kernel, it's a userspace ABI only).

No, see the source from Linux kernel:

https://github.com/torvalds/linux/blob/master/arch/x86/Kconf...

For all x86 processors, now there is a name "X86_32" which "depends on !64BIT" (i.e. 64BIT flag has to be off).

and there is a name "X86_64" which "depends on 64BIT" (i.e. 64BIT flag being on).

Under new convention X86 is a common prefix for both 32 and 64-bit kernels for x86 processors, and the suffix _32 means the kernel uses only 32bit instructions, and _64 that it uses 64bit instructions.

And also, there's handling of an old arch name "i386" which is recognized to mean 64BIT is off and if only "x86" is seen as arch name then there is a prompt that asks 64BIT yes or no. It also notes that the old name used for kernel with 64BIT off was "i386" and the old name used for kernel with 64BIT on was "x86_64".

Finally, the support for X32 ABI (allowing running executables which use 64-bit instructions but only "short" 32bit pointers in 64-bit kernel https://en.wikipedia.org/wiki/X32_ABI) is enabled in my 64-bit distro:

    ~$ sudo grep -P G_X86_X?\\d{2}= /boot/config-$(uname -r)
    CONFIG_X86_64=y
    CONFIG_X86_X32=y

The first line means this is a 64bit kernel for x86 processors, the second that X32 support is enabled on that kernel.

In short, there are two kinds of X86 kernels:

X86_32 -- formerly known as i386

X86_64 -- formerly known as x86_64

and an option for existence of X32 ABI in X86_64 called CONFIG_X86_X32.

Beatuiful, high-value reply. Thank you for making the connection to upstream and unpacking things with good, concise exposition.

No, that’s “x32”. “x86_32” is not an official name for anything, but based on the contents of the post, I believe Andy Lutomirski is using it to refer to 32-bit x86, aka i386.

And I believe he meant i686. Latest Intel CPU's with 32bit pointers.

x86-64 procesors can generally be run in IA32 compatibility mode. And intel still makes some IA32-only chips for embedded.

Your comment should be the top comment. I had no clue i386 and x86_32 where different. I though the article was saying 32bit linux is broken.... but no some strange "alternative" mode on linux is broken.... who cares.

The comment is wrong. It is about i386.