On DR7 is put the value 0x0155, that is all local breakpoint
flags are set and other flags are cleared.

I don't understand.

you have some luck, i decided to be friendly enough to pick up my intel system programming guide, and it fell open on exactly the right page (well, almost).

DR7 is the debug control register. L0 .. L3 are local breakpoint enable flags, and are placed on bit 0,2,4 and 6. that makes 0x55. now we still need to explain 0x100: ehm, just download the .pdf's on developer.intel.com

Nah. That would actually require limee to do some of his own homework, instead of just asking someone else to do it for him.

Regards,

When the Dr7 is set the value 0x155.The break point will be
invaild.When the Dr7 is Set the Value 0x00.The Break point
will be valid.I can't get it,yet.

Please give me some explain,thanks.

read the manual! if you need other people to answer questions with obvious answers your entire life, you won't get anywhere. the things you ask isn't part of some secret wisdom or something.