linux-kernel - Re: [PATCH] efi: Downgrade "EFI_MEMMAP is not enabled" message

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Date:   Fri, 01 Mar 2019 15:01:32 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     "Lee, Chun-Yi" <jlee@...e.com>,
        linux-efi <linux-efi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] efi: Downgrade "EFI_MEMMAP is not enabled" message

On Fri, 01 Mar 2019 14:53:39 +0100,
Ard Biesheuvel wrote:
> 
> On Fri, 1 Mar 2019 at 14:40, Takashi Iwai <tiwai@...e.de> wrote:
> >
> > Since 38ac0287b7f4 ("fbdev/efifb: Honour UEFI memory map attributes
> > when mapping the FB"), efifb_probe() checks its memory range via
> > efi_mem_desc_lookup(), and this leads to a spurious error message
> > "EFI_MEMMAP is not enabled" at every boot on KVM.  This is quite
> > annoying since the error message appears even if you set "quiet" boot
> > option.
> >
> > Actually there are only a few places that call efi_mem_desc_lookup()
> > function, and the other callers do give the explicit error messages
> > when the function returns an error in anyway.  That is, the error
> > message in the function is more or less moot.
> >
> > So let's downgrade the error message for stop annoying users.
> >
> > Fixes: 38ac0287b7f4 ("fbdev/efifb: Honour UEFI memory map attributes when mapping the FB")
> > Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1127339
> > Signed-off-by: Takashi Iwai <tiwai@...e.de>
> > ---
> >  drivers/firmware/efi/efi.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> > index 55b77c576c42..50ac33097458 100644
> > --- a/drivers/firmware/efi/efi.c
> > +++ b/drivers/firmware/efi/efi.c
> > @@ -409,7 +409,7 @@ int efi_mem_desc_lookup(u64 phys_addr, efi_memory_desc_t *out_md)
> >         efi_memory_desc_t *md;
> >
> >         if (!efi_enabled(EFI_MEMMAP)) {
> > -               pr_err_once("EFI_MEMMAP is not enabled.\n");
> > +               pr_debug("EFI_MEMMAP is not enabled.\n");
> >                 return -EINVAL;
> >         }
> >
> 
> efifb_probe() only calls efi_mem_desc_lookup() if
> screen_info.orig_video_isVGA == VIDEO_TYPE_EFI, which only gets
> assigned on a EFI boot.
> 
> So even though I don't object to the patch as is, I would like to
> understand where this error message is coming from, given that it
> means that you are running on a UEFI system without the EFI memory
> map.
> 
> Is this system booting via GRUB in EFI mode?

No, it's booted in legacy boot mode.  But the primary fb is efifb, and
that's why the message appears.


thanks,

Takashi