[edk2-devel] [edk2 PATCH] MdePkg: Use same ProcessorBind symbol define for RISCV64

[Michael D Kinney]

It is better if we can use the same include guard names, but is not 
strictly required for builds to work.

What is the specific error message seen when using the same include guard
names as other CPU types?

Include guards have 2 elements work discussing:
* Use of define names that start with '_' or '__' are reserved either by the 
  ANSI C spec or for compilers.  The historical use by EDK II code to start
  include guards with '_' could cause potential conflicts with some compilers
  and may need to be addressed everywhere.

* Modern compilers support #pragma once that provides the same feature and 
  may actually have some build performance benefits.  This is a better long term
  direction to remove the misuse of '_' and '__' and avoid potential collisions
  with ANSI C or compilers.  It also reduces the number of defines in an EDK II
  build.

	https://en.wikipedia.org/wiki/Pragma_once

Mike


> -----Original Message-----
> From: devel at edk2.groups.io <devel at edk2.groups.io> On Behalf Of Xue, Gavin
> Sent: Thursday, June 22, 2023 2:59 AM
> To: Pedro Falcato <pedro.falcato at gmail.com>
> Cc: devel at edk2.groups.io; sunilvl at ventanamicro.com; Warkentin, Andrei
> <andrei.warkentin at intel.com>; Wang, Yimin <yimin.wang at intel.com>; Sheng,
> Alan <alan.sheng at intel.com>
> Subject: Re: [edk2-devel] [edk2 PATCH] MdePkg: Use same ProcessorBind
> symbol define for RISCV64
> 
> Hi Pedro,
> 
> Thanks for your feedback.
> 
> The sample code what I listed in last mail is from/owned by another team,
> and I didn't find other special #ifndef case for RSIC-V building so far.
> RISC-V is an new processor architecture in edk2 implementation, in our
> internal BIOS code, there are many similar common code for edk2 and Windows
> app (for simulation).
> It's better if we can reuse existing code (mostly are from x86) and
> minimize modifications as much as possible. So I think use same guard name
> is make sense.
> How about your comments? Thanks.
> 
> Best regards,
> Gavin
> 
> -----Original Message-----
> From: Pedro Falcato <pedro.falcato at gmail.com>
> Sent: Wednesday, June 21, 2023 10:16 PM
> To: Xue, Gavin <gavin.xue at intel.com>
> Cc: devel at edk2.groups.io; sunilvl at ventanamicro.com; Warkentin, Andrei
> <andrei.warkentin at intel.com>; Wang, Yimin <yimin.wang at intel.com>; Sheng,
> Alan <alan.sheng at intel.com>
> Subject: Re: [edk2-devel] [edk2 PATCH] MdePkg: Use same ProcessorBind
> symbol define for RISCV64
> 
> On Fri, Jun 16, 2023 at 4:52 PM Xue, Gavin <gavin.xue at intel.com> wrote:
> >
> > Hi Sunil/Pedro,
> >
> > 1. As you know, ProcessorBind.h file of CPU Architecture file declares
> sets of base types for edk2 code compiling.
> > So data type in edk2 code doesn't rely on specific compiler (msvc, gcc
> etc.), which is a good design.
> >
> > But in practice, for the purpose of reuse, some code can be built with
> edk2, and also can be built to a standalone application (e.g. Win App).
> > Just like below code piece:
> > ===========
> > #ifndef __WRAPPER_BASE_TYPES_H__
> > #define __WRAPPER_BASE_TYPES_H__
> >
> > //
> > // To avoid definition conflict during EDK2 build, it must include
> > // ProcessorBind.h before xxx.h
> > //
> > #ifndef __PROCESSOR_BIND_H__
> >
> > #include <stdint.h>
> > typedef uint8_t  UINT8;
> > ==========
> >
> > In this case, if this is a edk2 build, the code will refer to data types
> from ProcessorBind.h, otherwise, it will refer to stdint.h from compiler.
> >
> > 2. Regarding the guard name, it's same __PROCESSOR_BIND_H__ macro in
> AArch64/Arm/Ebc/Ia32/X64, but it is PROCESSOR_BIND_H_
> > in RiscV64 and LoongArh64. For above code, if we build BIOS for RISCV64,
> it will try to include stdint.h due to different guard name.
> >
> > I am not sure if we can use same guard name to keep code alignment, or
> give some comments. Thanks.
> 
> Hi,
> Hmm, interesting problem. Have you tried to #ifndef with some other
> define? Like, I don't know, MAX_UINTN or EFIAPI?
> 
> --
> Pedro
> 
> 
> 
> 



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