[RFC] Remove requirement of alignment to track from MBR scheme

[Marcel Moolenaar]

On May 23, 2011, at 11:43 PM, Andriy Gapon wrote:

> on 23/05/2011 20:38 Warner Losh said the following:
>> 
>> On May 23, 2011, at 10:35 AM, Marcel Moolenaar wrote:
>>> I think we've had enough rushed and ill thought-out changes going
>>> in already and I can see that not aligning MBR partitions on a track
>>> boundary is potentially perceived as a PITA violation.
> 
> _PITA_ violation? :-)
> As to POLA - yeah, I can see people getting astonished that finally FreeBSD got
> its sh*t together and did the right thing, years after all other OSes (even
> Winddows) had done it.

:-)

Well, I just initialized a USB stick on my Mac and I see that it
still adheres to some notion of geometry:

	:
ugen3.2: <ITE Tech Inc.> at usbus3
umass0: <ITE Tech Inc. USB FLASH STORAGE, class 0/0, rev 2.00/2.00, addr 2> on usbus3
da0 at umass-sim0 bus 0 scbus0 target 0 lun 0
da0: <Simple Bonzai Xpress 2.20> Removable Direct Access SCSI-2 device 
da0: 1.000MB/s transfers
da0: 499MB (1023484 512 byte sectors: 64H 32S/T 499C)
GEOM: da0s1: EBR has non empty bootcode.
GEOM: msdosfs/MAC: EBR has non empty bootcode.
marcelm-server% gpart show da0
=>     32  1023424  da0  MBR  (499M)
       32       31       - free -  (15k)
       63  1023372    1  fat32  (499M)
  1023435       21       - free -  (10k)


gpart synthesized a 64 head, 32 sectors/track geometry, which
is not the same as the 63 sectors/track that Mac synthesized.
Yes, this demonstrates the bogosity of geometry, but it also
shows that it still exists.

All I'm saying: be careful.

-- 
Marcel Moolenaar
xcllnt at mac.com