Pierre,

Pierre Neidhardt wrote:
> need the "sg" and "sr_mod" kernel modules.  lsmod tells me they 
> are not
> loaded.

At the risk of pointing out the obvious:

  $ grep -E "CHR_DEV_SG|BLK_DEV_SR" 
  /run/current-system/kernel/.config
  CONFIG_BLK_DEV_SR=y
  # CONFIG_BLK_DEV_SR_VENDOR is not set
  CONFIG_CHR_DEV_SG=y

lsmod only lists, well, modules.

Kind regards,

T G-R