On Wed, 4 Dec 2002, Daniel Jacobowitz wrote: > Sorry, by "not handy" I meant I didn't have the manuals available :) 'http://www.mips.com/Documentation/R4400_Uman_book_Ed2.pdf' or see under "Publications"/"R4000...". There are other sources of the book available, e.g. somewhere within SGI web pages. R10k implements a single watchpoint this way, too. > > What do you think? > > You don't reveal to userland what size watchpoints are available - i.e. > how large a watchpoint can be. Does the mask match the hardware > implementation, and what are the restrictions on it? For that you set up a disabled watchpoint with a mask set to all ones (or the range you are interested in). Then when you retrieve it, you may see which bits stayed at ones. Similarly you may check for hardwired don't-cares by using a mask with all zeroes. The mask may differ for each watchpoint, e.g. for R4650 it's different for IWatch and DWatch, so you really want to have a per-watchpoint setting. Also the MIPS32/64 ISA specification implies a mask need not be contiguous. Similarly you may check for access types permitted, by enabling all of them (or ones you are interested in) and seeing which ones remained enabled. Per-watchpoint, again. I'd prefer not to overdesign the API leaving as much information as possible passed as is. This way userland gets more control over what's available. Maciej -- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +
