On Wed, 2011-01-05 at 17:14 +0200, Avi Kivity wrote: > On 01/05/2011 04:57 PM, Alex Williamson wrote: > > A valid argument. I think it could also be argued that the user is > > providing ownership of the file and writing to the file is part of the > > low level details of the sysfs rom file API and should be handled by the > > user of that API. We basically have 3 places we could put this: > > > > A. kernel - Why is this file mode 0400 by default anyway if using > > it requires write access? Set it to mode 0600 here by default. > > B. libvirt - Already does chown, why not do chmod too? chmod and > > restore here. > > C. qemu - Owns file, chmod is trivial and part of the sysfs rom > > file API? chmod around usage. > > > > qemu might not actually own the file, just have rw permissions. Or it > might own the file and selinux may prevent it from changing the > permissions. Or it may die before the reverse chmod and leave things > not as they were. > > > I chose qemu because it seemed to have the least chance of side-effects > > and has the smallest usage window. Do you prefer libvirt or kernel? > > No idea really. What's the kernel's motivation for keeping it ro? Sanity? > > I'd guess libvirt is the one to do it, but someone more familiar with > device assignment / pci (you?) should weigh in on this. I think I'll try the kernel first. Digging back through bitkeeper, this file has been read-only since it was introduced. It looks like maybe the enabling/disabling write was a request by Linus, so perhaps it's simply a bug that the file never got S_IWUSR permission when the extra logic was added. If so, there's no point in qemu or libvirt working around a trivial kernel bug. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
