On Thu, Jun 01, 2023 at 01:45:35PM +0500, Muhammad Usama Anjum wrote: > Hi, > > I've been looking into a problem where Windows applications misbehave > across suspend/resume when run on Wine on x86. These applications see time > going backwards. The timestamp counter (TSC) is reset when system resumes. > In case of Windows on Intel and AMD, the timestamp is saved and restored > when the system resumes from suspend. > > These applications read timestamp by rdtsc directly. These calls cannot be > intercepted by Wine. The application should be fixed such that it handles > these scenarios correctly. But there are hundreds of applications which > cannot be fixed. So some support is required in Wine or kernel. There isn't > anything which Wine can do as rdtsc call directly reads the timestamp. The > only option is that we support something in kernel. > > As more and more things are being added to Wine, Windows application can be > run pretty easily on Linux. But this rdtsc is a big hurdle. What are your > thoughts on solving this problem? > > We are thinking of saving and restoring the timestamp counter at suspend > and resume time respectively. In theory it can work on Intel because of > TSC_ADJUST register. But it'll never work on AMD until: > * AMD supports the same kind of adjust register. (AMD has said that the > adjust register cannot be implemented in their firmware. They'll have to > add it to their hardware.) > * by manual synchronization in kernel (I know you don't like this idea. But > there is something Windows is doing to save/restore and sync the TSC) Wine could set TIF_NOTSC, which will cause it to run with CR4.TSD cleared and cause RDTSC to #GP, at which point you can emulate it.
