On 02/05/12 12:25, Paolo Bonzini wrote: > Il 02/05/2012 12:18, Christian Borntraeger ha scritto: >> Maybe that really points to the problem that we are trying to solve here. >> For a dasd device, there is usually a 4096 byte block size and on the host >> these 4096 arereported via getss and getpbsz. >> The geometry reported by the device driver is usually 15 head and 12 sectors >> per track, but actually means 12 sectors of 4096 bytes size (a track ~ 48k). >> >> What I want to achieve is that the guest view is identical to the host view >> for cyls, heads, secs, and all block sizes. > > I think what you want is _not_ to have the same view as the host. What > you want is simply to have a default that is consistent with what is > common on actual s390 disks.
Let me put it in another way: I want to have these values to match the _device_ that we are passing to the guest because several tools and the partition detection code for a compatible disk format (those that can be accessed by z/OS) needs those values to work properly. That of course means that the guest view is identical to the host view because both views describe a real property of the hardware. IOW the geometry for dasd devices is not an artifical number, it has some real meaning that has a influence on the data structures on the disk. Thing is, the easiest way of getting the hardware property is to query the host. Does that make the situation a bit clearer? Christian
