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

Heinrich Schuchardt
2020-03-31T13:08:06Z

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.

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