On 08/07/2014 02:06 AM, Ross Zwisler wrote: > On Wed, 2014-08-06 at 14:33 +0300, Boaz Harrosh wrote: > > With this patch we end up in what feels like a weird place where we're half > using the old scheme of major/minor allocation, and half in the world of > dynamic major/minors. Devices have a major of 1 and minors that increment by > 1, but partitions have a major of 259 (BLOCK_EXT_MAJOR): > > brw-rw---- 1 root disk 1, 0 Aug 6 14:10 /dev/ram0 > brw-rw---- 1 root disk 1, 1 Aug 6 14:13 /dev/ram1 > brw-rw---- 1 root disk 259, 0 Aug 6 14:14 /dev/ram1p1 > brw-rw---- 1 root disk 259, 1 Aug 6 14:13 /dev/ram1p2 > brw-rw---- 1 root disk 259, 2 Aug 6 14:14 /dev/ram1p51 > This is when you use max_part = 1. If someone really cares, why would he care, but if he cares like if he wants persistent partition minors than he can use max_part = 8, say and it will all go nice. (And if he creates 9 partitions on a device then the last one will be from the 259 dynamic range) So you see it is all in the user choice. If he cares at all because I do not see why it matters > For NVMe and PRD you get a major of 259 all around: > > brw-rw---- 1 root disk 259, 0 Aug 6 16:55 /dev/pmem0 > brw-rw---- 1 root disk 259, 2 Aug 6 16:55 /dev/pmem0p1 > brw-rw---- 1 root disk 259, 3 Aug 6 16:55 /dev/pmem0p2 > brw-rw---- 1 root disk 259, 1 Aug 6 16:54 /dev/pmem1 > > It could be that this is fine, but it just smells fishy to me I guess. > If you go this way then dynamic creation with the mknod trick does not work because there is no association in the system with your driver. Whats so fishy I have read the all partitions code this is simple math really. This is the way it works. > Also, it looks like you can still create a new device with this patch, but you > can't create partitions on that device. Not sure if this is just what you get > when you dynamically create a device on the fly, or if it's a symptom of > something larger. > What? I just tried again this all works fine for me, here with fdisk. $ modprobe brd # will create ram0-7 $ mknod /dev/ram8 b 1 8 $ fdisk /dev/ram8 g, n, , , +2M, n, , , , , w I create 2 partitions 2M each and press w and it is all there. What numbers did you use ? rd_nr, max_part, and the mknod numbers. Here it just works fine. What did you try? Thanks Boaz -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
