Re: DEBUG() macros in DXE driver: can’t make it work in QEMU

[Laszlo Ersek <lersek@redhat.com>]

On 02/16/17 19:05, Andrew Fish wrote:
> 
>> On Feb 15, 2017, at 4:39 AM, Laszlo Ersek <lersek@redhat.com
>> <mailto:lersek@redhat.com>> wrote:
>>
>> On 02/15/17 01:00, David A. Van Arnem wrote:
>>>
>>>
>>> On 02/14/2017 04:46 PM, Nikolay Bodunov wrote:
>>>> Hi
>>>>
>>>> I red this topic before asking the question in the maillist.
>>>> Unfortunately,
>>>> it's not for DXE phase.
>>>> I even tried to use it and recieved expected compiler error:
>>>>
>>>> error 1001: Module type [PEIM] is not supported by library instance
>>>> [/home/nick/src/edk2/MdePkg/Library/UefiDebugLibConOut/
>>>> UefiDebugLibConOut.inf]
>>>>    consumed by [/home/nick/src/edk2/MdeModulePkg/Bus/Pci/
>>>> SdMmcPciHcPei/SdMmcPciHcPei.inf]
>>>
>>> Hi,
>>>
>>> MdePkg/Library/UefiDebugLibConOut/UefiDebugLibConOut.inf lists
>>> DXE_DRIVER in its [Defines] section under LIBRARY_CLASS, so it is
>>> compatible with DXE_DRIVER module types (I have used it this way).
>>> However, if I'm reading your output correctly, you are trying to build a
>>> PEI module which is why you are getting the error.  PEI is outside of my
>>> knowledge.
>>
>> In the PEI phase, no such thing exists as "system console" (that's a
>> UEFI construct), hence the fact that UefiDebugLibConOut (which prints to
>> said console) rejects being linked into PEIMs (PEI modules) is justified.
>>
>> Again, a suitable DebugLib instance should be chosen (in the DSC file
>> where the PEIM in question is listed too, resolving the DebugLib class
>> for PEIMs), and DEBUG() macros should be used for logging.
>>
> 
> The build system is very flexible and can be a bit confusing. I find it
> useful to generate a report by passing --report-file=REPORTFILE  to the
> build command. This will generate a report that will tell you per driver
> what libraries actually got linked (include libraries that libraries
> depend on). it will show all the fixed PCD settings as visible to the
> driver. If an FV was constructed it will also show the Depex that
> determines dispatch order, and again this can be changed by the
> libraries that get used. 
> 
> The idea behind the flexibility was that a chip or card vendor could
> write code using #include <Library/DebugLib.h> and link against DebugLib
> and it would work for any platform. Actually you could have multiple
> platforms in a single repository that share that code that all use
> different debug strategies, without the need to change chip or card
> vendor code. Thus we kind of had a push the configuration choices into
> the platform build kind of mind set.
> 
> Well the problem with flexibility is complexity, and that is what the
> build logs help with.

I agree. I don't know why I failed to mention the report file, as it is
part of my OvmfPkg / ArmVirtPkg build wrapper scripts. The report file
is super useful; I frequently consult it. (For PCDs too.)

Thanks!
Laszlo