Is Linux for Losers? part 2

Lok Technologies, a San Jose, Calif.-based maker of networking gear, started out using Linux in its equipment but switched to OpenBSD four years ago after company founder Simon Lok, who holds a doctorate in computer science, took a close look at the Linux source code.

"You know what I found? Right in the kernel, in the heart of the operating system, I found a developer's comment that said, 'Does this belong here?' "Lok says. "What kind of confidence does that inspire? Right then I knew it was time to switch."

Here is my conversation with a friend. And below is the attached code of BSD. Note line 126.

hussein: did he look at the BSD source code?
hussein: does he know that he can find exactly the same things in there?
hussein: http://fxr.watson.org/fxr/source//amd64/include/pmap.h#L126 <-- take a look at this
hussein: BSD source code
hussein: * XXX doesn't really belong here I guess...
hussein: very interesting comment
hussein: just like the one in Linux, hmmmmm?
hussein: really

/*
116 * The *PDI values control the layout of virtual memory
117 */
118 #define PML4PML4I (NPML4EPG/2) /* Index of recursive pml4 mapping */
119
120 #define KPML4I (NPML4EPG-1) /* Top 512GB for KVM */
121 #define DMPML4I (KPML4I-1) /* Next 512GB down for direct map */
122
123 #define KPDPI (NPDPEPG-2) /* kernbase at -2GB */
124
125 /*
126 * XXX doesn't really belong here I guess...
127 */
128 #define ISA_HOLE_START 0xa0000
129 #define ISA_HOLE_LENGTH (0x100000-ISA_HOLE_START)
130
131 #ifndef LOCORE