Re: Sparse minor space in ub

[Jan Engelhardt]

>On Wed, Jun 14, 2006 at 11:54:04PM -0700, Pete Zaitcev wrote:
>> --- linux-2.6.17-rc5/Documentation/devices.txt	2006-05-25 14:02:59.000000000 -0700
>> +++ linux-2.6.17-rc5-lem/Documentation/devices.txt	2006-05-25 15:45:34.000000000 -0700
>> @@ -2552,10 +2552,10 @@ Your cooperation is appreciated.
>>  		 66 = /dev/usb/cpad0	Synaptics cPad (mouse/LCD)
>>  
>>  180 block	USB block devices
>> -		0 = /dev/uba		First USB block device
>> -		8 = /dev/ubb		Second USB block device
>> -		16 = /dev/ubc		Thrid USB block device
>> -		...
>> +		  0 = /dev/uba		First USB block device
>> +		 16 = /dev/ubb		Second USB block device
>> +		 32 = /dev/ubc		Third USB block device
>> +		    ...
>
>I don't think that distros that have a static /dev will like this change
>at all :(
>
>Anyway to put the extra partitions some where else in the minor range?

(a)
  come with something up like glibc's compatibility scheme for high device 
  numbers, ie.

    minor = ((ubdisk & 0x1F)  << 4) | (ubpart & 0x03) |
            ((ubdisk & ~0x1F) << 9) | ((ubpart & 0x08) << 8)

  bits 10 09 08 | 07 06 05 04 03 02 01 00
  old              d  d  d  d  d  p  p  p
  new ..d  d  p |  d  d  d  d  d  p  p  p

  Would give the usual 16 partitions. But see (b).


(b)
  "181 block" seems free.
  Suggestion: have block-major-180 be ub disks with 8 parts max (and marked 
  as deprecated)
  and block-major-181 be ub disks with 16 parts max



Jan Engelhardt
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