I've always wondered:  what exactly do these do from release to
release?  Even a quick pointer to some code would help me.

I ask, because XFree86 4 (Feb. 6 sup) won't even try to run on the Alpha
(Feb.6 sup) without COMPAT_14 defined.  And if I try to add COMPAT_13
_and_ COMPAT_14 and recompile, or remove the COMPAT's altogether, I get
this:

[begin inserted text]

(II) VGA: Generic VGA driver (version 4.0) for chipsets: generic
(--) Assigning device section with no busID to primary device
(--) Chipset virge vx found
(**) S3VIRGE(0): Depth 24, (--) framebuffer bpp 24
(==) S3VIRGE(0): RGB weight 888
(==) S3VIRGE(0): Default visual is TrueColor
(==) S3VIRGE(0): Using HW Cursor
(==) S3VIRGE(0): Using fb.
(II) S3VIRGE(0): initializing int10
(II) dense base = 0x300000000
(II) has_bwx = 0
(II) Machine needs sparse mapping
(II) dense base = 0x300000000
(II) memBase = mmap(0, 0x100000000, ... 0x300000000)
(II) dense base = 0x300000000
(II) memory base = 0x200000000
(II) memSBase = mmap(0, 0x100000000, ... 0x200000000)
(II) memory base = 0x200000000
(II) memSBase = 0xffffffffffffffff, memBase = 0xffffffffffffffff

Fatal server error:
xf86MapVidMem: Could not mmap framebuffer (Cannot allocate memory)

[end inserted text]

With COMPAT_14 alone, it "works" (notwithstanding the fatal PLT errors
documented in another thread).

Thanks much,
--David