CODEWITHSUNDEEP
linux-kernelpci-e
keye
keye

Reputation: 125

Should pci_resource_start(pdev, bar) return same physical address in each boot?

I have noticed pci_resource_start(pdev, bar) returns different address in each boot on the same machine. If it returns a 'physical address', shouldn't it be consistent on same machine? Am I missing something?

Upvotes: 2

Views: 1339

Answers (1)

prl
prl

Reputation: 12457

The BIOS and/or the OS allocates address space for each device on each boot. There's no requirement for consistency from one boot to the next, but one would expect the algorithms to be deterministic. Any change to the system hardware or boot parameters could cause it to vary. (For example, even leaving a USB device plugged in across boot could conceivably cause variation.) I haven't noticed address space assignment changing when rebooting without any other changes.

Upvotes: 1

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