Re: [Qemu-devel] BUG: RTC issue when Windows guest is idle

[Alex Bligh]

On 30 Oct 2013, at 00:44, Xiexiangyou wrote:

> But I want to know why alarm timer will make the problem, is the reason that 
> losing the alarm event?

I am not sure it was the use of alarm timers per se - doubtless it would be
possible to write code that worked 100% using alarm timers. The old code
had accumulated over years and had grown somewhat crufty - no one's fault
in particular - so there were various inconsistencies relating to edge
cases (infinite timeouts, no timers running, no FDs, >UINT32_MAX timeouts
etc). I just remember seeing several times bits of code that made me
think "I wonder if and how that can ever work in situation X" and not
investigating further as the replacement code was generic enough to
work in all situations. And if there were bugs in the alarm timer bit
they will simply have been deleted when I deleted several hundred lines
of qemu-timer.c. Sometimes a rewrite just fixes stuff without
any particular bug-hunting skill on the part of the author.

-- 
Alex Bligh