On Tue, 2010-03-16 at 15:22 +0900, Tejun Heo wrote: > Hello, James. > > On 03/16/2010 03:14 PM, James Bottomley wrote: > > So, it is true to say that picking a certain H/S geometry (which is > > entirely withing the gift of the partitioner) will align msdos label > > partitions, but will be don't care for all other labels: all other > > partition labels (like gpt) use block as offset and don't have any truck > > with the fictitious C/H/S stuff. > > For any modern Linux and Windows, CHS simply doesn't matter. They > don't look at it at all. If they have a msdos label, they do. > > The big problem is that 99% of the x86 systems out there still use the > > ancient msdos label for their boot disks, so aligning H/S going forwards > > will give us a nice "just works" for x86 boxes. > > What I don't get is that how picking up a custom geometry can make > things work when there is *no* reliable way to determine which > geometry was used during partitioning once the partitioning is > complete. For msdos labels, it's embedded in the label ... for all other labels, it's made up on the spot. > Most BIOSs these days will simply report the geometry as > being 255/63 regardless of the geometry used during partitioning. So, > how can using a custom geometry give that nice "just works" for x86 > boxes when nobody knows what geometry is in use? Because the msdos label can only partition in units of cylinders. If you're using an msdos label, picking the right H/S gets you alignment. James -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
