On Thu, Apr 9, 2020 at 7:33 AM Liu, Jingqi <address@hidden> wrote:
On 4/8/2020 5:42 PM, Joao Martins wrote:
On 4/8/20 3:25 AM, Liu, Jingqi wrote:
On 4/8/2020 2:28 AM, Joao Martins wrote:
On 4/7/20 5:55 PM, Dan Williams wrote:
On Tue, Apr 7, 2020 at 4:01 AM Joao Martins <address@hidden> wrote:
Perhaps, you meant instead:
/sys/dev/char/%d:%d/align
Hmm, are you sure that's working?
It is, except that I made the slight mistake of testing with a bunch of wip
patches on top which one of them actually adds the 'align' to child dax device.
Argh, my apologies - and thanks for noticing.
I expect the alignment to be found
in the region device:
/sys/class/dax:
/sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus1/region1/dax1.1/dax1.0
$(readlink -f /sys/dev/char/253\:263)/../align
$(readlink -f /sys/dev/char/253\:263)/device/align
/sys/bus/dax:
/sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus1/region1/dax1.0/dax1.0
$(readlink -f /sys/dev/char/253\:265)/../align
$(readlink -f /sys/dev/char/253\:265)/device/align <-- No such file
The use of the /sys/dev/char/%d:%d/device is only supported by the
deprecated /sys/class/dax.
Hi Dan,
Thanks for your comments.
Seems it is a mistake.
It should be: $(readlink -f /sys/dev/char/253\:263)/../../align
Hmm, perhaps you have an extra '../' in the path? This works for me:
# ls $(readlink -f /sys/dev/char/252\:0/../align)
/sys/devices/platform/e820_pmem/ndbus0/region0/dax0.0/dax0.0/../align
# cat $(readlink -f /sys/dev/char/252\:0)/../align
2097152
# cat /sys/dev/char/252\:0/../align
2097152
Hi Joao,
Hmm, I need to have an extra '../' in the path. The details are as follows:
# ll /dev/dax2.0
crw------- 1 root root 251, 5 Mar 20 13:35 /dev/dax2.0
# uname -r
5.6.0-rc1-00044-gb19e8c684703
# readlink -f /sys/dev/char/251\:5/
/sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus0/region2/dax2.1/dax/dax2.0
# ls $(readlink -f /sys/dev/char/251\:5)/../align
ls: cannot access
'/sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus0/region2/dax2.1/dax/dax2.0/../align':
No such file or directory
# ls $(readlink -f /sys/dev/char/251\:5)/../dax_region/align
ls: cannot access
'/sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus0/region2/dax2.1/dax/dax2.0/../dax_region/align':
No such file or directory
# ls $(readlink -f /sys/dev/char/251\:5)/../../align
/sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus0/region2/dax2.1/dax/dax2.0/../../align
# ls $(readlink -f /sys/dev/char/251\:5)/../../dax_region/align
/sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus0/region2/dax2.1/dax/dax2.0/../../dax_region/align
# lsmod|grep pmem
dax_pmem_compat 16384 0
device_dax 20480 1 dax_pmem_compat
dax_pmem_core 16384 1 dax_pmem_compat
# lsmod|grep dax
dax_pmem_compat 16384 0
device_dax 20480 1 dax_pmem_compat
dax_pmem_core 16384 1 dax_pmem_compat
Seems some configurations are different ?
Can you share your info as above ? Thanks.
Alternatively maybe you can use libdaxctl that automatically handles
the ABI differences between compat-dax-class and dax-bus layouts? I
didn't recommend it before because I was not sure about qemu's policy
about taking on new library dependencies, but with libdaxctl you could
do something like (untested):
path = g_strdup_printf("/sys/dev/char/%d:%d", major(st.st_rdev),
minor(st.st_rdev));
rpath = realpath(path, NULL);
daxctl_region_foreach(ctx, region)
if (strstr(daxctl_region_get_path(region), rpath)) {
align = daxctl_region_get_align(region);
break;
}