Re: [PATCH v4 09/34] efi: Add EFI uclass for media

AKASHI Takahiro
2021-11-08T05:29:56Z

On Sun, Nov 07, 2021 at 09:43:22AM -0700, Simon Glass wrote:
> Hi Heinrich,
>
> On Sun, 7 Nov 2021 at 01:21, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
> >
> >
> >
> > On 11/4/21 04:09, Simon Glass wrote:
> > > At present UCLASS_EFI is used to represent an EFI filesystem among other
> > > things. The description of this uclass is "EFI managed devices" which is
> > > pretty vague. The only driver that uses this uclass is in fact not a real
> > > U-Boot driver, since its operations do not include a struct udevice.
> > >
> > > Rather than mess with this, create a new UCLASS_EFI_MEDIA uclass to handle
> > > EFI media such as disks. Make this the uclass to use for EFI media so that
> > > it can be used with 'part list', for example.
> > >
> > > The existing implementation using UCLASS_EFI remains as is, for
> > > discussion.
> > >
> > > Signed-off-by: Simon Glass <sjg@chromium.org>
> > > ---
> > >
> > > (no changes since v2)
> > >
> > > Changes in v2:
> > > - Add MAINTAINERS entry
> > > - Show the correct interface type with 'part list'
> > > - Update the commit message to explain things better
> > >
> > > MAINTAINERS | 3 +++
> > > arch/sandbox/dts/test.dts | 4 ++++
> > > disk/part.c | 5 ++++-
> > > drivers/block/Kconfig | 23 +++++++++++++++++++++++
> > > drivers/block/Makefile | 3 +++
> > > drivers/block/blk-uclass.c | 2 +-
> > > drivers/block/efi-media-uclass.c | 15 +++++++++++++++
> > > drivers/block/sb_efi_media.c | 20 ++++++++++++++++++++
> > > include/dm/uclass-id.h | 1 +
> > > test/dm/Makefile | 1 +
> > > test/dm/efi_media.c | 24 ++++++++++++++++++++++++
> > > 11 files changed, 99 insertions(+), 2 deletions(-)
> > > create mode 100644 drivers/block/efi-media-uclass.c
> > > create mode 100644 drivers/block/sb_efi_media.c
> > > create mode 100644 test/dm/efi_media.c
> > >
> > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > index 00ff572d4d2..3e8f10c72fa 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -712,8 +712,11 @@ W: https://u-boot.readthedocs.io/en/latest/develop/uefi/u-boot_on_efi.html
> > > F: board/efi/efi-x86_app
> > > F: configs/efi-x86_app*
> > > F: doc/develop/uefi/u-boot_on_efi.rst
> > > +F: drivers/block/efi-media-uclass.c
> > > +F: drivers/block/sb_efi_media.c
> > > F: lib/efi/efi_app.c
> > > F: scripts/build-efi.sh
> > > +F: test/dm/efi_media.c
> > >
> > > EFI PAYLOAD
> > > M: Heinrich Schuchardt <xypron.glpk@gmx.de>
> > > diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
> > > index 8cd688e8d26..2cea4a43c87 100644
> > > --- a/arch/sandbox/dts/test.dts
> > > +++ b/arch/sandbox/dts/test.dts
> > > @@ -498,6 +498,10 @@
> > > compatible = "sandbox,clk-ccf";
> > > };
> > >
> > > + efi-media {
> > > + compatible = "sandbox,efi-media";
> > > + };
> > > +
> > > eth@10002000 {
> > > compatible = "sandbox,eth";
> > > reg = <0x10002000 0x1000>;
> > > diff --git a/disk/part.c b/disk/part.c
> > > index a6a8f7052bd..2560f6a50bc 100644
> > > --- a/disk/part.c
> > > +++ b/disk/part.c
> > > @@ -296,8 +296,11 @@ static void print_part_header(const char *type, struct blk_desc *dev_desc)
> > > case IF_TYPE_VIRTIO:
> > > puts("VirtIO");
> > > break;
> > > + case IF_TYPE_EFI:
> > > + puts("EFI");
> > > + break;
> > > default:
> > > - puts ("UNKNOWN");
> > > + puts("UNKNOWN");
> > > break;
> > > }
> > > printf (" device %d -- Partition Type: %s\n\n",
> > > diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
> > > index 56a4eec05ac..755fdccb574 100644
> > > --- a/drivers/block/Kconfig
> > > +++ b/drivers/block/Kconfig
> > > @@ -61,6 +61,29 @@ config TPL_BLOCK_CACHE
> > > help
> > > This option enables the disk-block cache in TPL
> > >
> > > +config EFI_MEDIA
> > > + bool "Support EFI media drivers"
> > > + default y if EFI || SANDBOX
> > > + help
> > > + Enable this to support media devices on top of UEFI. This enables
> > > + just the uclass so you also need a specific driver to make this do
> > > + anything.
> > > +
> > > + For sandbox there is a test driver.
> > > +
> > > +if EFI_MEDIA
> > > +
> > > +config EFI_MEDIA_SANDBOX
> > > + bool "Sandbox EFI media driver"
> > > + depends on SANDBOX
> > > + default y
> > > + help
> > > + Enables a simple sandbox media driver, used for testing just the
> > > + EFI_MEDIA uclass. It does not do anything useful, since sandbox does
> > > + not actually support running on top of UEFI.
> > > +
> > > +endif # EFI_MEDIA
> > > +
> > > config IDE
> > > bool "Support IDE controllers"
> > > select HAVE_BLOCK_DEVICE
> > > diff --git a/drivers/block/Makefile b/drivers/block/Makefile
> > > index 94ab5c6f906..3778633da1d 100644
> > > --- a/drivers/block/Makefile
> > > +++ b/drivers/block/Makefile
> > > @@ -14,3 +14,6 @@ obj-$(CONFIG_IDE) += ide.o
> > > endif
> > > obj-$(CONFIG_SANDBOX) += sandbox.o
> > > obj-$(CONFIG_$(SPL_TPL_)BLOCK_CACHE) += blkcache.o
> > > +
> > > +obj-$(CONFIG_EFI_MEDIA) += efi-media-uclass.o
> > > +obj-$(CONFIG_EFI_MEDIA_SANDBOX) += sb_efi_media.o
> > > diff --git a/drivers/block/blk-uclass.c b/drivers/block/blk-uclass.c
> > > index 83682dcc181..2db7ce5de20 100644
> > > --- a/drivers/block/blk-uclass.c
> > > +++ b/drivers/block/blk-uclass.c
> > > @@ -44,7 +44,7 @@ static enum uclass_id if_type_uclass_id[IF_TYPE_COUNT] = {
> > > [IF_TYPE_SATA] = UCLASS_AHCI,
> > > [IF_TYPE_HOST] = UCLASS_ROOT,
> > > [IF_TYPE_NVME] = UCLASS_NVME,
> > > - [IF_TYPE_EFI] = UCLASS_EFI,
> > > + [IF_TYPE_EFI] = UCLASS_EFI_MEDIA,
> >
> > Don't break existing code. Create a new if_type here.
>
> My understanding is that this is not actually used at present. The
> tests appear to pass without trouble.
>
> What problem are you seeing?

I can agree with Simon's claim that the notion of UCLASS_EFI sounds vague.
In my understanding, it is expected to represent any UEFI driver/application
who will convert "UEFI protocol" to "U-Boot device", the only example
right now is "efi_block" device.

One of issues that I can see is that any instance of UCLASS_EFI doesn't
appear in DM tree. I have made an experimental patch which makes UCLASS_EFI
a pseudo U-Boot device. DM tree would look like:
root
|-- 'EFI block driver' (CLASS_EFI for block_io_protocol)
|-- 'efi_blk' (CLASS_BLK with TYPE_EFI)

This way, the meaning of UCLASS_EFI should be much clearer?

# In fact, the actual implementer of BLOCK_IO_PROTOCOL is
# a loaded UEFI application, though.

-Takahiro Akashi

> Regards,
> Simon