On Thu, Jul 30, 2020 at 01:38:41PM +0200, Florian Weimer wrote: > * Daniel P. Berrangé: > > > I'm not familiar with what COPR is doing for s39x0 ? Is it using the > > simple QEMU linux-user syscall emulation, or is it running a proper > > QEMU s390x VM. > > > > I'm guessing probably the former. The linux-user syscall emulation is > > truely amazing, but it is certainly not feature complete or fully > > robust. > > It still implements vfork using fork, right? This means we should > likely fix posix_spawn in glibc to support this deviation from the > kernel interface. Other Linux emulations have exactly the same problem. Yeah, all of fork(), vfork() and clone(), end up getting mapped onto fork() or pthread_create() depending the precise set of CLONE_* flags required. Common helper for all: https://gitlab.com/qemu-project/qemu/-/blob/master/linux-user/syscall.c#L172 https://gitlab.com/qemu-project/qemu/-/blob/master/linux-user/syscall.c#L6086 And then the syscall wiring vfork: https://gitlab.com/qemu-project/qemu/-/blob/master/linux-user/syscall.c#L10792 fork: https://gitlab.com/qemu-project/qemu/-/blob/master/linux-user/syscall.c#L7882 clone: https://gitlab.com/qemu-project/qemu/-/blob/master/linux-user/syscall.c#L9792 there's no clone2/clone3 support at all either. > For emulating 32-bit targets, we have a broken readdir/telldir/seekdir > implementation in glibc on 64 bit host kernels because we try to use > d_ino directly, which is 64 bit and does not fit into the long value > that POSIX requires. A kernel patch with a new interface has been > posted which would work around this has been proposed, but it is not > going anywhere. > The second issue also affects full-system virtualization if p9fs (not > sure what the right name is, it's the older pass-through file system) is > used. But it's specific to 32 bit, so maybe not that important after > all. Yep, 9p, its generally not great POSIX emulation no matter what. The more modern virtio-fs is a more promising solution for the future, based on FUSE. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx
