Strange error when starting sis6326 driver

[walt]

X.Org X Server 1.4.0
Release Date: 5 September 2007
X Protocol Version 11, Revision 0
Build Operating System: FreeBSD 7.0-STABLE i386

(II) Setting vga for screen 0.
(II) SIS(0): SiS driver (2005/09/20-1, compiled for X.org 1.4.0.0)
(--) SIS(0): Chipset is SiS6326 AGP (H0) (revision 0x0b)
(--) SIS(0): Relocated I/O registers at 0xCC80
(==) SIS(0): Write-combining range (0xa0000,0x10000) was already clear
(II) Loading sub module "ramdac"
(II) LoadModule: "ramdac"(II) Module "ramdac" already built-in
(==) SIS(0): Depth 24, (==) framebuffer bpp 32
(EE) SIS(0): **************************************************
(EE) SIS(0):                       ERROR:
(EE) SIS(0): Framebuffer bpp 32 not supported for this chipset
(EE) SIS(0):                   END OF MESSAGE
(EE) SIS(0): **************************************************

I just updated this old FreeBSD machine from XF86 to xorg, and all
was working okay before, so the hardware is fine.

Where did that 32 bpp come from?  The xorg.conf was generated by
the Xorg server and it says nothing about 32 bits anywhere, and I
can't see any way in the documentation to change it.

Anyone but me still using a sis6326?

Thanks for any clues.