mlxreg: can't write large registers

[kcgthb]

Hi!

I'm trying to use mlxreg --set to update a switch's node description, but it looks like there's an issue with register sizes, that may be larger than the maximum register size that can be sent in-band.

Specifically, I can read the SPZR register just fine:

# mlxreg -d /dev/mst/SW_MT54000_sh03-isw-c03_lid-0x0010 --reg_name SPZR --get --indexes "swid=0x0"
Sending access register...

Field Name              | Data
=====================================
enh_sw_p0               | 0x00000000
ng                      | 0x00000000
sig                     | 0x00000000
mp                      | 0x00000000
vk                      | 0x00000000
cm                      | 0x00000000
enh_sw_p0_mask          | 0x00000000
ndm                     | 0x00000000
cm2                     | 0x00000000
swid                    | 0x00000000
capability_mask         | 0x4450c848
system_image_guid_h     | 0x1c34da03
system_image_guid_l     | 0x004f6244
node_guid_h             | 0x1c34da03
node_guid_l             | 0x004f6244
v_key_h                 | 0x00000000
v_key_l                 | 0x00000000
capability_mask2        | 0x0000003b
max_pkey                | 0x00000008
node_description[0]     | 0x73683033
node_description[1]     | 0x2d697377
node_description[2]     | 0x2d633033
node_description[3]     | 0x00000000
node_description[4]     | 0x00000000
node_description[5]     | 0x00000000
node_description[6]     | 0x00000000
node_description[7]     | 0x00000000
node_description[8]     | 0x00000000
node_description[9]     | 0x00000000
node_description[10]    | 0x00000000
node_description[11]    | 0x00000000
node_description[12]    | 0x00000000
node_description[13]    | 0x00000000
node_description[14]    | 0x00000000
node_description[15]    | 0x00000000
=====================================

But setting a value for node_description[0] fails with -E- Failed to send access register: Register is too large:

# mlxreg -d /dev/mst/SW_MT54000_sh03-isw-c03_lid-0x0010 --reg_name SPZR --set "ndm=0x1,node_description[0]=0x74657374" --indexes "swid=0x0"
You are about to send access register: SPZR with the following data:
Field Name              | Data    
=====================================
enh_sw_p0               | 0x00000000
ng                      | 0x00000000
sig                     | 0x00000000
mp                      | 0x00000000
vk                      | 0x00000000
cm                      | 0x00000000
enh_sw_p0_mask          | 0x00000000
ndm                     | 0x00000001
cm2                     | 0x00000000
swid                    | 0x00000000
capability_mask         | 0x4450c848
system_image_guid_h     | 0x1c34da03
system_image_guid_l     | 0x004f6244
node_guid_h             | 0x1c34da03
node_guid_l             | 0x004f6244
v_key_h                 | 0x00000000
v_key_l                 | 0x00000000
capability_mask2        | 0x0000003b
max_pkey                | 0x00000008
node_description[0]     | 0x74657374
node_description[1]     | 0x2d697377
node_description[2]     | 0x2d633033
node_description[3]     | 0x00000000
node_description[4]     | 0x00000000
node_description[5]     | 0x00000000
node_description[6]     | 0x00000000
node_description[7]     | 0x00000000
node_description[8]     | 0x00000000
node_description[9]     | 0x00000000
node_description[10]    | 0x00000000
node_description[11]    | 0x00000000
node_description[12]    | 0x00000000
node_description[13]    | 0x00000000
node_description[14]    | 0x00000000
node_description[15]    | 0x00000000
=====================================

 Do you want to continue ? (y/n) [n] : y
 Sending access register...
-E- Failed to send access register: Register is too large

This seems to be related to the fact that the SPZR register has a size of 0x70, while the maximum register size authorized to be sent inband is 0x2c (INBAND_MAX_REG_SIZE = 44, as defined here:

mstflint/mtcr_ul/mtcr_ul_com.c

Line 2700 in 45e11fb

#define INBAND_MAX_REG_SIZE 44

There's same issue with both mlxreg from MFT and mstreg from mstflint.

What would be the best way around this?
Thanks!

[tomer540]

fix for this issue can be found in master_devel branch as part of PR#540.
the fix will also be included on the next master release

[kcgthb]

The issue doesn't seem to be fixed in MFT 4.20:

# mst version
mst, mft 4.20.0-34, built on Apr 25 2022, 20:48:31. Git SHA Hash: 62bbc33

# mlxreg -d lid-8 --reg_name SPZR --set "ndm=0x1,node_description[0]=0x666f6f6f"  --indexes "swid=0x0"
You are about to send access register: SPZR with the following data:
Field Name              | Data
=====================================
enh_sw_p0               | 0x00000000
ng                      | 0x00000000
sig                     | 0x00000000
mp                      | 0x00000000
vk                      | 0x00000000
cm                      | 0x00000000
enh_sw_p0_mask          | 0x00000000
ndm                     | 0x00000001
cm2                     | 0x00000000
swid                    | 0x00000000
capability_mask         | 0x4450d848
system_image_guid_h     | 0x1c34da03
system_image_guid_l     | 0x004f6244
node_guid_h             | 0x1c34da03
node_guid_l             | 0x004f6244
capability_mask2        | 0x0000003b
max_pkey                | 0x00000008
node_description[0]     | 0x666f6f6f
node_description[1]     | 0x2d697377
node_description[2]     | 0x2d633033
node_description[3]     | 0x00000000
node_description[4]     | 0x00000000
node_description[5]     | 0x00000000
node_description[6]     | 0x00000000
node_description[7]     | 0x00000000
node_description[8]     | 0x00000000
node_description[9]     | 0x00000000
node_description[10]    | 0x00000000
node_description[11]    | 0x00000000
node_description[12]    | 0x00000000
node_description[13]    | 0x00000000
node_description[14]    | 0x00000000
node_description[15]    | 0x00000000
=====================================

 Do you want to continue ? (y/n) [n] : y
 Sending access register...
-E- Failed to send access register: Register is too large

[kcgthb]

The same issue is still present in MFT 4.21.

@tomer540 could you please clarify if MFT >= 4.20 is supposed to include the fix from PR#540?

[tomer540]

i will check with relevant owners and update you.

[tomer540]

It seems only the 'get' command was fixed, the 'set' has some internal issues.
The team and I are working on a solution for it.
I will update master_devel branch as soon we have it.

[kcgthb]

Thanks @tomer540 !

[kcgthb]

@tomer540 long overdue update, but I just wanted to confirm that this issue has been fixed in MFT 4.22.
Thanks a lot!

[kcgthb]

Closing #329

[tomer540]

I am happy I was able to help, even if it took so long