dmpstore Deep Dive
How to use UEFI Shell dmpstore to inspect boot variables, Secure Boot variables, setup variables, and NVRAM state during firmware debug.
A boot option disappears after a BIOS update.
Windows says nothing useful. Setup shows a different boot order. The customer says the SSD is still installed.
Before touching the OS, check the firmware variable store.
Shell> dmpstore BootOrder
Shell> dmpstore Boot0000
Shell> dmpstore BootNextWhat dmpstore really shows
UEFI variables are not just key-value pairs. A useful debug view includes:
| Item | Value | Note |
|---|---|---|
| Variable name | BootOrder, Boot0001, SecureBoot | The human-visible variable name. |
| Vendor GUID | Namespace owner | Variables with the same name but different GUID are different variables. |
| Attributes | NV, BS, RT, authenticated | Shows whether the variable persists and when it is accessible. |
| Data | Raw bytes | May encode EFI_LOAD_OPTION, key database content, setup structure, or simple flags. |
Real world example: BootOrder exists but boot still fails
Shell> dmpstore BootOrder
BootOrder: 0003 0001 0000
Shell> dmpstore Boot0003
Boot0003: ... HD(...) / File(\EFI\Microsoft\Boot\bootmgfw.efi)This proves only that BDS has a boot option. It does not prove the path is valid.
Next checks:
BootOrder points to Boot0003
↓
Boot0003 contains EFI_LOAD_OPTION
↓
Device Path points to disk / partition / file
↓
Shell map confirms the filesystem exists
↓
File path exists under ESPSecure Boot checks
Shell> dmpstore SecureBoot
Shell> dmpstore SetupMode
Shell> dmpstore PK
Shell> dmpstore KEK
Shell> dmpstore db
Shell> dmpstore dbxFor Secure Boot investigation, SecureBoot=1 alone is not enough. SetupMode, key presence, and db/dbx state matter.
Common pitfall: dumping everything creates noise
Shell> dmpstoreThis can produce a huge output. For targeted debug, dump only the variables you need first.
Debug checklist
When using dmpstore
Treat the output as firmware state evidence.
Related notes
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