Re: [libvirt] [PATCH v2 1/2] Add pcihole64 attribute to root PCI controllers

On 08/13/2013 11:54 AM, Daniel P. Berrange wrote: > On Tue, Aug 13, 2013 at 11:53:42AM +0200, Ján Tomko wrote: >> On 08/13/2013 10:55 AM, Daniel P. Berrange wrote: >>> On Tue, Aug 13, 2013 at 10:51:04AM +0200, Ján Tomko wrote: >>>> <controller type='pci' index='0' model='pci-root' pcihole64='1'/> >>>> >>>> It can be used to adjust (or disable) the size of the 64-bit >>>> PCI hole. The size attribute is in gigabytes, since it would >>>> get rounded up to nearest GB by QEMU anyway. >>> >>> Choosing the units based on what one specific hypervisor happens to >>> currently do has proven to be a pretty bad idea in the past. I'd say >>> we should be using KB here. Or better yet, have this as a separate >>> child element, and then support a 'units' attribute at the same time, >>> defaulting to KB. >>> >> >> Would it be okay to use the largest usable unit when formatting the XML >> to make it more human-friendly? > > No, because you'd be throwing away data if the user had requested less > than a GB. Outputting XML should use the smallest unit for which we > want to support, which IMHO should be KB. > By 'usable' I meant the unit that is the largest divisor of the size, e.g.: 512 KB would stay 512 KB, but 2048 MB would get translated to 2 GB.

But this requires the applications parsing the XML to read both the size and the units.