Re: [Qemu-devel] icount and tb chaining

[Peter Maydell]

On 18 January 2012 19:43, James Greensky <address@hidden> wrote:
> On Tue, Jan 17, 2012 at 7:03 PM, 陳韋任 <address@hidden> wrote:
>> I think those numbers (0, 1, and 2) means tb_add_jump 2nd parameter here, so
>> it's intentionally to check jmp_first when n is 2. Since tb->jmp_first is 
>> never
>> to be zero, then condition is always false (do nothing) when n is 2.

> Chenwj, you are correct, the check bypasses the whole function, I was
> not paying enough attention to that check, it should never be null, in
> which case the code doesn't get executed and the chaining remains
> unchanged.

The question that occurs to me is, is this working like this by design,
or is it a bug that just happens to have no ill effects? The fact that
the condition in tb_add_jump() is commented as "only needed for thread
safety" suggests the latter to me...

-- PMM