[U-Boot] [PATCH] efi: Update README.efi to clarify build and test instructions

[Bin Meng]

Hi Igor,

On Fri, Aug 14, 2015 at 7:46 PM, Stoppa, Igor <igor.stoppa at intel.com> wrote:
> Hi Bin,
>
> On 14 August 2015 at 13:47, Bin Meng <bmeng.cn at gmail.com> wrote:
>> The doc has a misleading 'make menuconfig' when building the EFI
>> application and payload. Clarify this and also update information
>> on test with QEMU.
>>
>> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
>> ---
>>
>>  doc/README.efi | 28 ++++++++++++++++++----------
>>  1 file changed, 18 insertions(+), 10 deletions(-)
>>
>> diff --git a/doc/README.efi b/doc/README.efi
>> index 7c95579..e4872ed 100644
>> --- a/doc/README.efi
>> +++ b/doc/README.efi
>> @@ -49,18 +49,21 @@ Build Instructions
>>  First choose a board that has EFI support and obtain an EFI implementation
>>  for that board. It will be either 32-bit or 64-bit.
>
> Here I would add something like:
>
> Alternatively, you can opt for using QEMU and the OVMF, as detailed below.
>

OK.

>>
>> -To build U-Boot as an EFI application (32-bit EFI required), enable
>> -CONFIG_EFI and CONFIG_EFI_APP. The efi-x86 config is set up for this.
>> +To build U-Boot as an EFI application (32-bit EFI required), enable CONFIG_EFI
>> +and CONFIG_EFI_APP. The efi-x86 config (efi-x86_defconfig) is set up for this.
>>
>> -To build U-Boot as an EFI payload (32-bit or 64-bit EFI can be used), adjust
>> -an existing config to enable CONFIG_EFI, CONFIG_EFI_STUB and either
>> -CONFIG_EFI_STUB_32BIT or CONFIG_EFI_STUB_64BIT.
>> +To build U-Boot as an EFI payload (32-bit or 64-bit EFI can be used), adjust an
>> +existing config (like qemu-x86_defconfig) to enable CONFIG_EFI, CONFIG_EFI_STUB
>> +and either CONFIG_EFI_STUB_32BIT or CONFIG_EFI_STUB_64BIT.
>
>
> It might also be useful to give a short explanation (or a link to a
> short explanation, if you know of any) of EFI application vs EFI
> payload.
>
> I'm still not sure I got that right, even after consulting the EFI specs.

It is already documented, see section "Inner workings" in the same file.

>
>>  Then build U-Boot as normal, e.g.
>>
>> +For building an EFI application, run:
>> +   make efi-x86_defconfig
>> +   make
>
> Why is this one named efi-x86_defconfig, while the other is not?
> Could it be efi-x86-application_defconfig, or something similarly
> stating what sort of EFI binary it is?

This is the default naming convention that U-Boot uses. U-Boot see a
*board*. The efi-x86 is a *board* that represents the EFI application.
In the future we may add efi-arm for ARM EFI application.

>
>> +For building an EFI payload, run:
>>     make qemu-x86_defconfig
>> -   make menuconfig    (or make xconfig if you prefer)
>> -   # change the settings as above
>>     make
>
> It is mostly redundant, but I'd still prefer to have a reference
> defconfig that just works also for the payload. Maybe not one for each
> word size, but at least one.

See my comments in another thread.

>
>>
>>  You will end up with one of these files:
>> @@ -71,8 +74,9 @@ You will end up with one of these files:
>>
>>  Trying it out
>>  -------------
>> -Qemu is an emulator and it can emulate an x86 machine. You can run the
>> -payload with something like this:
>> +QEMU [1] is an emulator and it can emulate an x86 machine. Please make sure
>> +your QEMU version is 2.3.0 or above to test this. You can run the payload with
>> +something like this:
>>
>>     mkdir /tmp/efi
>>     cp /path/to/u-boot*.efi /tmp/efi
>> @@ -80,7 +84,8 @@ payload with something like this:
>>
>>  Add -nographic if you want to use the terminal for output. Once it starts
>>  type 'fs0:u-boot-payload.efi'
>
> This didn't work for me, with the Tianocore binary
> I had to use uppercase for the drive name, as in:
>
> FS0:u-boot-payload.efi

This is probably out of this scope for this doc. I don't know if this
is something special related to how the prebuilt EFI BIOS was built,
but I built a BIOS from the source and it worked fine. And it even
worked without 'fs0' and just type 'u-boot-payload.efi'. You probably
could ask in the edk2 community.

>
>  to run the payload or 'fs0:u-boot-app.efi' to
>> -run the application. 'bios.bin' is the EFI 'BIOS'.
>> +run the application. 'bios.bin' is the EFI 'BIOS'. Check [2] to obtain a
>> +prebuilt EFI BIOS for QEMU or you can build one from source as well.
>>
>>  To try it on real hardware, put u-boot-app.efi on a suitable boot medium,
>>  such as a USB stick. Then you can type something like this to start it:
>> @@ -235,3 +240,6 @@ common/cmd_efi.c
>>  Ben Stoltz, Simon Glass
>>  Google, Inc
>>  July 2015
>> +
>> +[1] http://www.qemu.org
>> +[2] http://www.tianocore.org/ovmf/
>> --
>> 1.8.2.1
>>
>
> One more thing that I found somewhat confusing, but maybe it's just
> because of my very limited experience with U-Boot on x86: where is the
> prompt supposed to appear vs where is the logging happening?
>

I don't understand. U-Boot does not require login.

> In some cases the logging seems to go to the screen (that's what I
> used), but in some other cases the logging goes to a serial port.
> And maybe (but I could have misunderstood) it goes also to some
> reserved memory area (maybe inspected with an ICE/ICD tool?).
>
> --

Regards,
Bin