[U-Boot] [PATCH v2 2/3] efi_loader: disk: install FILE_SYSTEM_PROTOCOL only if available

[Heinrich Schuchardt]

On 10/3/19 9:09 AM, AKASHI Takahiro wrote:
> Heinrich,
>
> On Thu, Sep 12, 2019 at 06:51:35PM +0900, AKASHI Takahiro wrote:
>> On Thu, Sep 12, 2019 at 11:43:07AM +0200, Heinrich Schuchardt wrote:
>>> On 9/12/19 11:17 AM, AKASHI Takahiro wrote:
>>>> On Thu, Sep 12, 2019 at 10:57:20AM +0200, Heinrich Schuchardt wrote:
>>>>> On 9/12/19 6:51 AM, AKASHI Takahiro wrote:
>>>>>> In the current implementation, EFI_SIMPLEFILE_SYSTEM_PROTOCOL is always
>>>>>> installed to all the partitions even if some of them may house no file
>>>>>> system.
>>>>>>
>>>>>> With this patch, that protocol will be installed only if FAT file system
>>>>>> exists.
>>>>>>
>>>>>> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
>>>>>> ---
>>>>>>   lib/efi_loader/efi_disk.c | 16 +++++++++++++++-
>>>>>>   1 file changed, 15 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c
>>>>>> index 7a6b06821a47..d72f455901f2 100644
>>>>>> --- a/lib/efi_loader/efi_disk.c
>>>>>> +++ b/lib/efi_loader/efi_disk.c
>>>>>> @@ -9,6 +9,7 @@
>>>>>>   #include <blk.h>
>>>>>>   #include <dm.h>
>>>>>>   #include <efi_loader.h>
>>>>>> +#include <fs.h>
>>>>>>   #include <part.h>
>>>>>>   #include <malloc.h>
>>>>>>
>>>>>> @@ -217,6 +218,19 @@ efi_fs_from_path(struct efi_device_path *full_path)
>>>>>>   	return handler->protocol_interface;
>>>>>>   }
>>>>>>
>>>>>> +static int efi_fs_exists(struct blk_desc *desc, int part)
>>>>>> +{
>>>>>> +	if (fs_set_blk_dev_with_part(desc, part))
>>>>>> +		return 0;
>>>>>> +
>>>>>> +	if (strcmp(fs_get_type_name(), "fat"))
>>>>>
>>>>> Before your patch we could use any supported file system (e.g. EXT2). I
>>>>> see no need for a restriction to FAT. You could compare the string to
>>>>> "unsupported":
>>>>
>>>> No. As far as you want to stick to compliance to UEFI specification,
>>>> "fat" is the only file system supported by UEFI.
>>>
>>> In the case of device path node VenHw() there is a direct rule in the
>>> spec indicating how it should be rendered. I have not seen anything in
>>> the UEFI spec saying that you should not support file systems besides
>>> FAT. So there is no compliance issue. I would be reluctant to remove an
>>> existing capability of U-Boot.
>>
>> See section 13.3. It says,
>>          The file system supported by the Extensible Firmware Interface is
>>          based on the FAT file system.
>
> Any comments here?

The spec does not say: Thou shalt not support other file systems.

>
>>>>
>>>>> if (!strcmp(fs_get_type_name(), "unsupported"))
>>>>> 	return 0;
>>>>>
>>>>> But wouldn't it be preferable to have a function to access fs_type (in
>>>>> fs/fs.c) directly instead of a string representation?
>>>>
>>>> Agree, but there is no direct function in fs/fs.c.
>>>> I'm reluctant to invent a new function just for this purpose.
>>>
>>> In that case we should compare to a string that is defined as constant
>>> in fs.h.
>
> Are you saying that we should add new macros in fs.h?
> All the file system names are initialized in fs/fs.c now.
>
>> -Takahiro Akashi
>>
>>>
>>> Best regards
>>>
>>> Heinrich
>>>
>>>>
>>>> -Takahiro Akashi
>>>>
>>>>
>>>>> Otherwise we should convert the string "unsupported" of fstypes[] into a
>>>>> constant in fs.h so that we can be sure we are using the same value.
>>>>>
>>>>> Best regards
>>>>>
>>>>> Heinrich
>>>>>
>>>>>> +		return 0;
>>>>>> +
>>>>>> +	fs_close();
>>>>>> +
>>>>>> +	return 1;
>>>>>> +}
>>>>>> +
>>>>>>   /*
>>>>>>    * Create a handle for a partition or disk
>>>>>>    *
>>>>>> @@ -270,7 +284,7 @@ static efi_status_t efi_disk_add_dev(
>>>>>>   			       diskobj->dp);
>>>>>>   	if (ret != EFI_SUCCESS)
>>>>>>   		return ret;
>>>>>> -	if (part >= 1) {
>>>>>> +	if (part >= 1 && efi_fs_exists(desc, part)) {
>>>>>>   		diskobj->volume = efi_simple_file_system(desc, part,
>>>>>>   							 diskobj->dp);
>>>>>>   		ret = efi_add_protocol(&diskobj->header,
>>>>>>
>>>>>
>>>>
>>>
>