Bugzilla – Bug 1127339
kernel: efi: EFI_MEMMAP is not enabled
Last modified: 2022-07-21 17:27:19 UTC
Please say if this error in log can be safely ignored
> kernel: efi: EFI_MEMMAP is not enabled.
I noticed it on non-uefi jobs.
Kernel-folks, can you give your opinion as to whether or not this error is worthy of concern?
I don't think it's a serious problem, but certainly a thing that started appearing recently. Adding Joey to Cc.
Since it could be easily reproduced, I bisected. It leads to the commit
efi/esrt: Only call efi_mem_reserve() for boot services memory
Sorry, the bisection was incorrect. Now retrying...
OK, the second try lead to the commit
fbdev/efifb: Honour UEFI memory map attributes when mapping the FB
This sounds more reasonable. It's the commit introducing the efi_mem_desc_lookup() check at efifb_probe().
... and it means that the error message is harmless and nothing to worry much.
The call efi_mem_desc_lookup() inspects whether the given area has been reserved, so it should be OK even if it's not reserved.
The easiest "fix" would be to downgrade the message to pr_info*() or pr_debug*() instead of pr_err*(). Or we may add a flag not to spew errors, but I guess it's overkill. There are only a few places calling efi_mem_desc_lookup(). The other callers show the errors via pr_err() or err_warn() when an error is returned from the function, so showing an error in the function is almost superfluous.
Created attachment 798559 [details]
Test fix patch
I submitted the patch to usptream. Let's see whether it's accepted. Then we can backport to TW kernel.
(In reply to Takashi Iwai from comment #8)
> I submitted the patch to usptream. Let's see whether it's accepted. Then
> we can backport to TW kernel.
This went on to an interesting discussion, and the upstream dev suggested a better fix.
Will check and backport once when it's merged to upstream.
Created attachment 801843 [details]
Upstream fix patch
Now I pushed the upstream fix patch in the subsystem tree to stable branch.
Haven't been present in the latest runs. If no objections, I close this report.