Hi Karel, On 22 October 2012 19:58, Karel Zak <kzak@xxxxxxxxxx> wrote: > On Mon, Oct 22, 2012 at 06:15:57PM +0530, Venkatraman S wrote: >> blkid_probe_enable_topology(pr, 1); > > This is strings based interface (NAME=value). It's probably > better to use: > > tp = blkid_probe_get_topology(pr); > > blkid_topology_get_alignment_offset(tp); > > see libblkid/samples/topology.c. > > >> I am able to get to the property value (which is set from the sysfs >> value for the disk). >> >> But when mkswap is invokded with /dev/sdbX, then sysfs_probe is not >> able to discover the parent disk's sysfs property. > > Really? It should be able to translate the partition name to the > whole-disk name and us it. > > # ./sample-topology /dev/sdd1 > ----- binary interface: > alignment offset : 0 > minimum io size : 4096 > optimal io size : 262144 > logical sector size : 4096 > physical sector size : 4096 > ----- NAME=value interface (values: 4): > MINIMUM_IO_SIZE = 4096 > OPTIMAL_IO_SIZE = 262144 > PHYSICAL_SECTOR_SIZE = 4096 > LOGICAL_SECTOR_SIZE = 4096 > I understand. I assume this works because each of these are present in both /sys/block/sda/ and /sys/block/sdaX/. But I am seeking a new property (for which I have already coded the appropriate lookup hooks in topology.c) The property (device/preferred_erase_size is present usually in eMMC and SD cards, and not regular hard disks, and it only present in the root device node sysfs I think it would be easier for you after looking at the patches that I already have (crude with lots of hacks and debug). I'll post them now > > >> Any help would be great. > > What exactly is your goal? > My objective is to implement / experiment some of the ideas that were bounced around in kernel mailing list for optimizing swap on flash media [1] [2] and make compatible changes in both kernel and mkswap. The changes revolve around embedding useful information in swap header that the kernel can use to optimize it's swap algorithm. [1] https://lkml.org/lkml/2012/3/30/410 [2] http://thread.gmane.org/gmane.linux.kernel.mmc/14864 -- To unsubscribe from this list: send the line "unsubscribe util-linux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
