On 12/28/2011 01:40 PM, Peter Maydell wrote: > On 28 December 2011 10:42, Avi Kivity <a...@redhat.com> wrote: > > It's possible to check for an interrupt before every instruction, > > without any overhead: > > > > - when a signal arrives, check the instruction pointer. If it points > > outside tcg code, set a flag and return. > > - consult a table indexed by the instruction pointer, that gives the > > number of bytes to the next guest instruction boundary > > - if nonzero, set a breakpoint at that boundary, and resume > > - remove the breakpoint (if set) > > - adjust the TB to return on the current instruction pointer > > - return > > This assumes you have hardware breakpoints on your host, so > it's not portable.
You could also use software breakpoints. Or just temporarily replace the host instruction on the next guest instruction boundary with a return. > (You also need to add a check-and-handle-flag for every return > from a helper function to TCG code, ah yes - didn't consider that. you could put all helper in their own section, an do something around that - but that assumes no callouts from helpers to the standard library. > and of course you need to > actually create the instruction-boundary table. This should be well amortized. > These are both > overheads.) -- error compiling committee.c: too many arguments to function
