[U-Boot] [U-Boot,v3,03/21] efi: add some missing __packed

Peter Jones
2017-10-03T14:34:54Z

On Fri, Sep 15, 2017 at 06:53:39PM +0000, Heinrich Schuchardt wrote:
> On 09/14/2017 12:05 AM, Rob Clark wrote:
> > All of the device-path related structures should be packed. UEFI
> > defines the device-path as a byte-aligned data structure.
> >
> > Signed-off-by: Rob Clark <robdclark@gmail.com>
> > ---
> > include/efi_api.h | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/include/efi_api.h b/include/efi_api.h
> > index ec1b321e8e..175341348e 100644
> > --- a/include/efi_api.h
> > +++ b/include/efi_api.h
> > @@ -284,11 +284,11 @@ struct efi_device_path {
> > u8 type;
> > u8 sub_type;
> > u16 length;
> > -};
> > +} __packed;
> >
> > struct efi_mac_addr {
> > u8 addr[32];
>
> Hello Alex, hello Rob,
>
> 32 bytes is more than the 6 bytes than we need.
> Why was the structure defined this way?

It probably *should* have been variable length in the spec, but it is
defined as 32-bytes. But 6 is also not correct - it's right for
ethernet, but not for everything. I suspect they picked the length of
an IPoIB (Infiniband) MAC here.

>
> > -};
> > +} __packed;
> >
> > #define DEVICE_PATH_TYPE_MESSAGING_DEVICE 0x03
> > # define DEVICE_PATH_SUB_TYPE_MSG_MAC_ADDR 0x0b
> > @@ -297,7 +297,7 @@ struct efi_device_path_mac_addr {
> > struct efi_device_path dp;
> > struct efi_mac_addr mac;
> > u8 if_type;
> > -};
> > +} __packed;
> >
> > #define DEVICE_PATH_TYPE_MEDIA_DEVICE 0x04
> > # define DEVICE_PATH_SUB_TYPE_FILE_PATH 0x04
> > @@ -305,7 +305,7 @@ struct efi_device_path_mac_addr {
> > struct efi_device_path_file_path {
> > struct efi_device_path dp;
> > u16 str[32];
>
> Where do we get this 32 from?
> Couldn't file/directory names be shorter (1 character) or longer (255
> characters)?

Note there's already another patch in this series fixing this.

--
Peter