On Mon, Feb 08, 2016 at 03:20:47PM -0500, John Snow wrote: > On 02/08/2016 08:14 AM, Roman Kagan wrote: > > On Fri, Feb 05, 2016 at 07:25:07PM +0100, Igor Mammedov wrote: > >>> + aml_append(fdi, > >>> + aml_int(cylinders - 1)); /* Maximum Cylinder Number */ > >> this puts uint64_t(-1) in AML i.e. cylinders == 0 and overflow happens here > >> > >> CCing Jon > > > > I guess this is the effect of John's fdc rework. I used to think zero > > geometry was impossible at the time this patch was developed. > > > > I wonder if it hasn't been fixed already by > > > > commit fd9bdbd3459e5b9d51534f0747049bc5b6145e07 > > Author: John Snow <js...@redhat.com> > > Date: Wed Feb 3 11:28:55 2016 -0500 > > > > fdc: fix detection under Linux > > Yes, hopefully solved on my end. The geometry values for an empty disk > are not well defined (they certainly don't have any *meaning*) so if you > are populating tables based on an empty drive, I just hope you also have > the mechanisms needed to update said tables when the media changes.
I don't. At the time the patch was developed there basically were no mechanisms to update the geometry at all (and this was what you patchset addressed, in particular, wasn't it?) so I didn't care. Now if it actually has to be fully dynamic it's gonna be more involved... > What do the guests use these values for? Are they fixed at boot? Only Windows guests use it so it's hard to tell. I can only claim that if I stick bogus values into that ACPI object the guest fails to read the floppy. Roman.
