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

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

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@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?

> > >
> > >> 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,
> > >>>
> > >>
> > >
> >