Hi Peter, Thanks for highlighting this.
Regards, Arnabjyoti Kalita On Wed, May 16, 2018 at 9:14 AM, Peter Maydell <peter.mayd...@linaro.org> wrote: > On 15 May 2018 at 22:09, Arnabjyoti Kalita <akal...@cs.stonybrook.edu> > wrote: > > I was trying to understand what the function tcg_qemu_tb_exec() returns. > I > > can understand that the last two bits of the return value contain the > exit > > status of the translation block that just got executed. However I cannot > > understand what the remaining bits in the value point to. I find it hard > to > > understand what it returns from the source code. > > > > Basically, I am finding it hard to determine if this function returns the > > current TB that was executed or that it returns the next TB that is to be > > executed. > > That depends on the value in the bottom two bits. If the bottom two > bits are 2 or 3, then the pointer part is the TB we were about to > execute but abandoned execution of. If the bottom two bits are 0 or 1, > then the return value is whatever we passed to tcg_gen_exit_tb() > when we were generating the code for the exit path for the TB we > just executed. The pointer part will either be 0, or the address > of that just-executed TB. (We use this to try to link the > just-executed TB to the next one, so 0 means "don't try to link".) > > thanks > -- PMM >
