Option to constrain linux-user exec() to emulated CPU only

Bug #1912107 reported by Mingye Wang
This bug affects 2 people
Affects Status Importance Assigned to Milestone

Bug Description

When trying to reproduce a bug someone reported on an actual AMD K10[1], ​I tried to directly throw `qemu_x86-64 -cpu
​phenom path/to/wrongly-labelled-instruction-set/gcc 1.c` at the problem, but failed to get an "illegal instruction" as expected. A quick investigation reveals that the error is actually caused by one of gcc's child processess, and that the said process is being ran directly on the host. A similar problem happens with trying to call stuff with /usr/bin/env.

 ​[1]: https://github.com/Homebrew/brew/issues/1034

Since both the host and the guest are x86_64, I deemed binfmt inapplicable to my case. I believe that QEMU should offer a way to modify exec() and other spawning syscalls so that execution remains on an emulated CPU in such a case. Call it an extra layer of binfmt, if you must.

Revision history for this message
Thomas Huth (th-huth) wrote :

The QEMU project is currently moving 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 the bug state to "Incomplete" now.

If the bug has already been fixed in the latest upstream version of QEMU,
then please close this ticket as "Fix released".

If it is not fixed yet and you think that this bug report here is still
valid, then you have two options:

1) If you already have an account on gitlab.com, please open a new ticket
for this problem in our new tracker here:


and then close this ticket here on Launchpad (or let it expire auto-
matically after 60 days). Please mention the URL of this bug ticket on
Launchpad in the new ticket on GitLab.

2) If you don't have an account on gitlab.com and don't intend to get
one, but still would like to keep this ticket opened, then please switch
the state back to "New" or "Confirmed" within the next 60 days (other-
wise it will get closed as "Expired"). We will then eventually migrate
the ticket automatically to the new system (but you won't be the reporter
of the bug in the new system and thus you won't get notified on changes

Thank you and sorry for the inconvenience.

tags: added: feature-request linux-user
Changed in qemu:
status: New → Incomplete
Mingye Wang (artoria2e5)
Changed in qemu:
status: Incomplete → Confirmed
status: Confirmed → New
Revision history for this message
Thomas Huth (th-huth) wrote : Moved bug report

This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'expired' now.
Please continue with the discussion here:


Changed in qemu:
status: New → Expired
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