The Debian project supports a wide range of hardware architectures, including 32-bit x86 CPUs. Changes are happening in Debian's development branches which will make older versions of the 32-bit architecture obsolete. Ben Hutchings provides the details: "Last year it was decided to increase the minimum CPU features for the i386 architecture to 686-class in the Stretch release cycle. This means dropping support for 586-class and hybrid 586/686 processors. (Support for 486-class processors was dropped, somewhat accidentally, in Squeeze.) This was implemented in the Linux kernel packages starting with Linux 4.3, which was uploaded to Unstable in December last year. In case you missed that change, GCC for i386 has recently been changed to target 686-class processors and is generating code that will crash on other processors. Any such systems still running Testing or
Unstable will need to be switched to run Stable (Jessie)." A list of processors which will no longer be supported after Debian "Jessie" can be found in Hutchings' mailing list post.