[PATCH 09/16] efi_loader: imply FAT, FAT_WRITE

AKASHI Takahiro
2020-04-01T07:04:04Z

On Wed, Apr 01, 2020 at 08:31:10AM +0200, Heinrich Schuchardt wrote:
> On 4/1/20 3:14 AM, AKASHI Takahiro wrote:
> > On Wed, Apr 01, 2020 at 08:57:33AM +0900, AKASHI Takahiro wrote:
> >> On Tue, Mar 31, 2020 at 03:08:06PM +0200, Heinrich Schuchardt wrote:
> >>> On 2020-03-31 09:44, AKASHI Takahiro wrote:
> >>>> On Tue, Mar 31, 2020 at 08:44:02AM +0200, Heinrich Schuchardt wrote:
> >>>>> On March 31, 2020, 5:28 a.m. UTC Takahiro Akashi wrote:
> >>>>>> On Fri, Mar 27, 2020 at 06:27:53AM +0100, Heinrich Schuchardt wrote:
> >>>>>>> The UEFI spec requires support for the FAT file system.
> >>>>>>>
> >>>>>>> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
> >>>>>>> ---
> >>>>>>> lib/efi_loader/Kconfig | 2 ++
> >>>>>>> 1 file changed, 2 insertions(+)
> >>>>>>>
> >>>>>>> diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> >>>>>>> index 9890144d41..e10ca05549 100644
> >>>>>>> --- a/lib/efi_loader/Kconfig
> >>>>>>> +++ b/lib/efi_loader/Kconfig
> >>>>>>> @@ -15,6 +15,8 @@ config EFI_LOADER
> >>>>>>> select HAVE_BLOCK_DEVICE
> >>>>>>> select REGEX
> >>>>>>> imply CFB_CONSOLE_ANSI
> >>>>>>> + imply FAT
> >>>>>>> + imply FAT_WRITE
> >>>>>>
> >>>>>> Obviously, this *imply* doesn't enforce enabling FAT.
> >>>>>> If it is absolutely necessary, another measure should be taken.
> >>>>>
> >>>>> If somebody wants to minimize the U-Boot size it might be necessary to
> >>>>> do without FAT_WRITE or FAT support.
> >>>>
> >>>> If so, Get/SetVariable won't be supported even in boot time
> >>>> with your patch applied. It is not practical for almost all users.
> >>>
> >>> Hello Akashi,
> >>>
> >>> without FAT_WRITE we will not have persistence for variables.
> >>> SetVariable and GetVariable are still usable.
> >>
> >> How about CONFIG_FAT?
> >
> > (=> What if !CONFIG_FAT)

?

> >
> >
> > More fundamentally,
> > Why do you want to use a file as storage device for variables?
> > why not raw partition (or just part of partition) on, say,
> > NOR or eMMC?
> >
> > As you know, EDK2 saves variables directly on NOR (or block device?
> > probably).
>
> Yes, we may add further stores later on.

Why not now?
How will you generalize it?

> Ilias wants to use the RPMB
> area of eMMC devices.

I think that he plans to use RPMB as secure storage for Standalone MM.

> As an EFI system partition exists on any UEFI
> compatible device I think implementing this first is a valid approach.

I don't deny your approach here, but
I expect that more generic framework for back storage be
implemented and FAT driver be on top of that.

-Takahiro Akashi

>
> Best regards
>
> Heinrich
>
> >
> > -Takahiro Akashi
> >
> >> -Takahiro Akashi
> >>
> >>> Best regards
> >>>
> >>> Heinrich
> >>>
> >>>>
> >>>>>>
> >>>>>> In addition, why do you treat FAT specifically here?
> >>>>>> I remember that you insisted that other file system should be
> >>>>>> allowed on U-Boot when I posted some patch.
> >>>>>
> >>>>> An EFI system partition is always FAT formatted. So if we want to safe
> >>>>> U-Boot variables to the EFI system partition we require FAT.
> >>>>
> >>>> As system partition is required to be in FAT, file system used on
> >>>> other partitions must also be in FAT since, as I said before,
> >>>> UEFI specification clearly defines its file system format based on FAT.
> >>>> See section 13.3.
> >>>>
> >>>> So,
> >>>>
> >>>>>> I remember that you insisted that other file system should be
> >>>>>> allowed on U-Boot when I posted some patch.
> >>>>
> >>>> You reverted your statement above here.
> >>>> That is my point.
> >>>>
> >>>> -Takahiro Akashi
> >>>>
> >>>>> Best regards
> >>>>>
> >>>>> Heinrich
> >>>>>
> >>>>>>
> >>>>>> -Takahiro Akashi
> >>>>>>
> >>>>>>
> >>>>>>> imply USB_KEYBOARD_FN_KEYS
> >>>>>>> imply VIDEO_ANSI
> >>>>>>> help
> >>>>>>> --
> >>>>>>> 2.25.1
> >>>
>