I guess from the search strings that are leading people here that someone out there has just set their students Rosamond McKitterick’s The Uses of Literacy in Early Medieval Europe as part of this week’s reading. I can’t really help you with that except to say, do wherever you’re studying read the Susan Kelly paper, as it’s one of the very few pieces of work out there in English that pauses to think about how individual charters come to be written at all.1
However, I can help the person that was looking for a biography of Mir Geribert, the self-acclaimed princeps Olerdulae. There is one, though it’s in Catalan and I’ve never seen it, by Ramon Planes, called Mir Geribert, Príncep d’Olèrdola. And that you probably found out for yourself, but maybe you can’t easily get hold of it.2 So I recommend that you instead try and find Pierre Bonnassie’s magnum opus, La Catalogne, and soak up the account of the baronial revolt in vol. 2.3 Yes, it is in French, but I’m afraid in this particular corner of Europe there really aren’t any English options. There comes a point where you have to try reading something else.
1. S. Kelly, “Anglo-Saxon Lay Society and the Written Word” in R. McKitterick (ed.), The Uses of Literacy in Early Mediaeval Europe (Cambridge: CUP 1990), pp. 36-62.
2. R. Planes, Mir Geribert, Príncep d’Olèrdola (Barcelona: Dalmau 1970). It’s only 54 pages.
3. P. Bonnassie, La Catalogne du Milieu du Xe à la Fin du XIe Siècle: croissance et mutations d’une société (Toulouse 1975-1976), 2 vols, II pp. 625-646 & 674-680.