[Qemu-devel] [Bug 1652373] [NEW] User-mode QEMU is not deterministic

[Qemu-devel] [Bug 1652373] [NEW] User-mode QEMU is not deterministic

[Lluís Vilanova]

Public bug reported:

QEMU in user-mode (linux-user or bsd-user) has no way to get the
equivalent of the "-icount" argument found in softmmu mode.

It is true that some system calls in user-mode can prevent deterministic
execution, but it would be very simple to patch time-related syscalls to
return a number based on icount when in deterministic mode.

Putting both changes together (icount + time-related syscalls) would
cover the needs for deterministic execution of most benchmarks (i.e.,
those not interacting with the network or other programs in the system).

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1652373

Title:
  User-mode QEMU is not deterministic

Status in QEMU:
  New

Bug description:
  QEMU in user-mode (linux-user or bsd-user) has no way to get the
  equivalent of the "-icount" argument found in softmmu mode.

  It is true that some system calls in user-mode can prevent
  deterministic execution, but it would be very simple to patch time-
  related syscalls to return a number based on icount when in
  deterministic mode.

  Putting both changes together (icount + time-related syscalls) would
  cover the needs for deterministic execution of most benchmarks (i.e.,
  those not interacting with the network or other programs in the
  system).

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[Bug 1652373] Re: User-mode QEMU is not deterministic

[Thomas Huth]

The QEMU project is currently considering to move its bug tracking to another system. For this we need to know which bugs are still valid and which could be closed already. Thus we are setting all older bugs to
"Incomplete" now.
If you still think this bug report here is valid, then please switch the state back to "New" within the next 60 days, otherwise this report will be marked as "Expired". Thank you and sorry for the inconvenience.


** Changed in: qemu
       Status: New => Incomplete

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You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1652373

Title:
  User-mode QEMU is not deterministic

Status in QEMU:
  Incomplete

Bug description:
  QEMU in user-mode (linux-user or bsd-user) has no way to get the
  equivalent of the "-icount" argument found in softmmu mode.

  It is true that some system calls in user-mode can prevent
  deterministic execution, but it would be very simple to patch time-
  related syscalls to return a number based on icount when in
  deterministic mode.

  Putting both changes together (icount + time-related syscalls) would
  cover the needs for deterministic execution of most benchmarks (i.e.,
  those not interacting with the network or other programs in the
  system).

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1652373/+subscriptions

[Bug 1652373] Re: User-mode QEMU is not deterministic

[Launchpad Bug Tracker]

[Expired for QEMU because there has been no activity for 60 days.]

** Changed in: qemu
       Status: Incomplete => Expired

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1652373

Title:
  User-mode QEMU is not deterministic

Status in QEMU:
  Expired

Bug description:
  QEMU in user-mode (linux-user or bsd-user) has no way to get the
  equivalent of the "-icount" argument found in softmmu mode.

  It is true that some system calls in user-mode can prevent
  deterministic execution, but it would be very simple to patch time-
  related syscalls to return a number based on icount when in
  deterministic mode.

  Putting both changes together (icount + time-related syscalls) would
  cover the needs for deterministic execution of most benchmarks (i.e.,
  those not interacting with the network or other programs in the
  system).

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1652373/+subscriptions