Analysis to return Chassis type as string

1

I manage a bunch of Linux systems, servers, laptops, VMs. I need to determine the Chassis type of each system. I’m trying to write an analysis to take the value in /sys/class/dmi/id/chassis_type and then return with a string that tells us the Type. For instance, 1 is Other, 9 is Laptop, 23 is Rack Mount Chassis. I seem to be having problems on reading the value. I’m trying something like

(if it contains "23" then "Chassis" else if it contains "1" then "Other" else "") of file "/sys/class/dmi/id/chassis_type"

but get told The operator "contains" is not defined. Any help?

2

Would using the SMBIOS inspector yield the same results?

Q: (tuple string item ( (it as string as integer) of values "type" of structures "system_enclosure_or_chassis" of smbios ) of "Unknown, Other, Unknown, Desktop, Low Profile Desktop, Pizza Box, Mini Tower, Tower, Portable, Laptop, Notebook, Hand Held, Docking Station, All in One, Sub Notebook, Space-Saving, Lunch Box, Main System Chassis, Expansion Chassis, SubChassis, Bus Expansion Chassis, Peripheral Chassis, Storage Chassis, Rack Mount Chassis, Sealed-Case PC, Multi-system chassis, CompactPCI, AdvancedTCA, Blade, Blade Enclosure, Tablet, Convertible, Detachable") | ERROR "Unknown"
A: Desktop
T: 296

3

Almost. It works on a Dell Latitude 5550 and a VM, but a PowerEdge 660 returns User-defined error: Unknown. It seems like Bigfix’s DMI/SMBios is returning the wrong value.

Q: values "type" of structures "system_enclosure_or_chassis" of smbios

A: 151

I would expect it to be a value orf23, which is what the file says

# more /sys/class/dmi/id/chassis_type

23

4

That intrigued me, and when I spell it out in binary there's a solid relationship between the decimal numbers '151' and '23'.

q: 151 as bits
A: 10010111

q: 23 as bits
A:    10111

These are...the same value, but '151' also has the highest bit (value 128) as 'set' rather than 'cleared'. Otherwise, these are the same.

Sure enough, checking the DMI specification...'chassis_type' is a single byte, but it actually holds two different values. At https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.9.0.pdf , see page 1025, at offset 05h:

Offset 05h
Specification Verion: 2.0+
Name: Type
Length: BYTE
Value: Varies
Description:
Bit 7 Chassis lock is present if 1. Otherwise, either a lock is not present, or it is unknown if theenclosure has a lock.

Bits 6:0 Enumeration value; see
below.

So, what does that all mean?
It means that for value 151, this is chassis_type 23 decimal, i.e. 0x17, or 'Rack Mount Chassis'; AND bit 7 is set, so it is 'Locked'.

Give me a few minutes to work on a more generalized form of the relevance to split up that value.

5

Try this form and see whether it gives the result you expect (you can remove the first item of the tuple if you don't care to check whether it's locked)

q: (if bit 7 of it then "Locked" else "Unlocked|Unknown") of (hexadecimal integer (it as hexadecimal) as bits) of values "type" of structures "system_enclosure_or_chassis" of smbios
A: Unlocked|Unknown
I: plural string

q: (tuple string item ((((it - (128 as bit set)) as integer) of  (hexadecimal integer (it as hexadecimal) as bits)) of values "type" of structures "system_enclosure_or_chassis" of smbios) of "Unknown, Other, Unknown, Desktop, Low Profile Desktop, Pizza Box, Mini Tower, Tower, Portable, Laptop, Notebook, Hand Held, Docking Station, All in One, Sub Notebook, Space-Saving, Lunch Box, Main System Chassis, Expansion Chassis, SubChassis, Bus Expansion Chassis, Peripheral Chassis, Storage Chassis, Rack Mount Chassis, Sealed-Case PC, Multi-system chassis, CompactPCI, AdvancedTCA, Blade, Blade Enclosure, Tablet, Convertible, Detachable") | ERROR "Unknown"
A: Notebook
I: singular string

q: ((if bit 7 of it then "Locked" else "Unlocked|Unknown") of (hexadecimal integer (it as hexadecimal) as bits) of values "type" of structures "system_enclosure_or_chassis" of smbios, (tuple string item ((((it - (128 as bit set)) as integer) of  (hexadecimal integer (it as hexadecimal) as bits)) of values "type" of structures "system_enclosure_or_chassis" of smbios) of "Unknown, Other, Unknown, Desktop, Low Profile Desktop, Pizza Box, Mini Tower, Tower, Portable, Laptop, Notebook, Hand Held, Docking Station, All in One, Sub Notebook, Space-Saving, Lunch Box, Main System Chassis, Expansion Chassis, SubChassis, Bus Expansion Chassis, Peripheral Chassis, Storage Chassis, Rack Mount Chassis, Sealed-Case PC, Multi-system chassis, CompactPCI, AdvancedTCA, Blade, Blade Enclosure, Tablet, Convertible, Detachable") | ERROR "Unknown")
A: Unlocked|Unknown, Notebook
I: plural ( string, string )
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6

Thanks Jason!

That’s giving me exactly what I need.

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