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

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Message-ID: <s5h5zt2el6d.wl-tiwai@suse.de>
Date:   Fri, 01 Mar 2019 15:14:34 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     Takashi Iwai <tiwai@...e.de>, "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 15:02:23 +0100,
Ard Biesheuvel wrote:
> 
> On Fri, 1 Mar 2019 at 15:01, Takashi Iwai <tiwai@...e.de> wrote:
> >
> > 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.
> >
> 
> So how are we ending up with
> 
> screen_info.orig_video_isVGA == VIDEO_TYPE_EFI
> 
> ??

Ah, sorry, my description was too ambiguous.

Actually our GRUB2 default setup boots the Linux kernel with linuxefi.
What I meant was that I invoked qemu-kvm without any -bios option, so
it's no EFI BIOS.


thanks,

Takashi