[shi2] shi2 < MC zyik < OC *[ml@k] (*Lj+k) 'eat'
si4 < MC ziH < OC *[z-l@k]? (*zlj+k) 'feed'

Schuessler, p. 544:

shi2 < *mlj@k "vb. To eat." [Shi 2/90092; Shu 155; JW 679; S 398; K. 921a]
si4 < *slj@kh "vb. To feed, give to eat." [JW 684; S 27; K. 921f]

Jäschke, p. 289:

ldag-pa, pf. bldags, fut. bldag, imp. ldog

From pre-Tibetan *'lak; the 'a-chung may be cognate to OC *m-, and OC *[@] corresponds regularly to Tibetan -a-.