On Wed, 2011-01-05 at 15:26 +0000, Daniel P. Berrange wrote: > On Wed, Jan 05, 2011 at 05:14:55PM +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. > > Agreed, I don't think we can rely on QEMU being able to chmod() the > file in general. > > > > > >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've no real objection to libvirt setting the 0600 permissions > on it, if that's required for correct operation. I'll try the kernel first, digging through history it looks more like a kernel bug. > BTW, what is the failure scenario seen when the file is 0400. > I want to know how to diagnose/triage this if it gets reported > by users in BZ... Nothing terrible; on older versions the option ROM contents won't contain the actual option rom, on newer versions, the ROM BAR doesn't even get added when the fopen fails. 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
