On Mon, 25 Jul 2022 at 12:13, Daniel P. Berrangé <berra...@redhat.com> wrote: > > On Mon, Jul 25, 2022 at 12:00:35PM +0100, Peter Maydell wrote: > > For handling guest POSIX timers, we currently use an array > > g_posix_timers[], whose entries are a host timer_t value, or 0 for > > "this slot is unused". When the guest calls the timer_create syscall > > we look through the array for a slot containing 0, and use that for > > the new timer. > > > > This scheme assumes that host timer_t values can never be zero. This > > is unfortunately not a valid assumption -- for some host libc > > versions, timer_t values are simply indexes starting at 0. When > > using this kind of host libc, the effect is that the first and second > > timers end up sharing a slot, and so when the guest tries to operate > > on the first timer it changes the second timer instead. > > For sake of historical record, could you mention here which specific > libc impl / version highlights the problem.
How about: "This can happen if you are using glibc's backwards-compatible 'timer_t is an integer' compat code for some reason. This happens when a glibc newer than 2.3.3 is used for a program that was linked to work with glibc 2.2 to 2.3.3." Laurent, I'm going to assume you don't need a v2 sending just for a commit message tweak, unless you'd like me to do that. thanks -- PMM
