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

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

On Thu, Oct 03, 2019 at 03:44:54PM +0200, Heinrich Schuchardt wrote:
> 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@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 we admit such an excuse for arbitrary extension,
it will easily break compatibility in general.

-Takahiro Akashi


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