other: 0.156
semantic: 0.101
device: 0.098
debug: 0.074
vnc: 0.074
PID: 0.074
performance: 0.067
graphic: 0.058
network: 0.057
files: 0.056
permissions: 0.055
socket: 0.050
boot: 0.046
KVM: 0.034
debug: 0.183
other: 0.183
files: 0.165
semantic: 0.107
performance: 0.056
network: 0.054
PID: 0.050
boot: 0.037
device: 0.036
permissions: 0.032
socket: 0.029
graphic: 0.026
vnc: 0.026
KVM: 0.017

qemu-x86_64 segment prefixes error

qemu-x86_64 version 4.1.0 (qemu-x86_64 version 4.0.0 also have the issue)

In 64-bit mode (x86_64) the DS, ES, SS or CS segment prefixes should be ignored; qemu-x86_64 does not ignore them.

example: an x86_64 instructions preceded by FS DS (0x64 0x26) segment prefixes have the linear address of its memory reference flat-mapped (as if DS was in action) whereas it should be FS-mapped (offset by FS_base, because the DS, ES, SS or CS are just ignored).


I attach a small C++ program that shows this discrepancy.

$ ./sample
I'm not in QEMU

$ qemu-x86_64 ./sample
I'm in QEMU



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 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". Or please mark it as "Fix Released" if
the problem has been solved with a newer version of QEMU already.

Thank you and sorry for the inconvenience.


Repro case in comment #1 still demonstrates bug.



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:

 https://gitlab.com/qemu-project/qemu/-/issues/267