Re: [PATCH v2 6/6] BaseTools/CommonLib: drop definition of MAX_UINTN

["David F." <df7729@gmail.com>]

I don't know, to me it's very clear that UINTN is talking about the target,
just like size_t would be.

There are/were a bunch of API's using UINTN so using UINTN was desirable,
and where needed UINTN_MAX.

I just don't see an advantage to removing it.   Do see disadvantage to
removing it for breaking existing code and for those that want the "native"
(best/fasted/most efficient) int size for the processor (similar again to
size_t)

On Tue, Dec 11, 2018 at 7:46 AM Laszlo Ersek <lersek@redhat.com> wrote:

> On 12/11/18 08:11, David F. wrote:
> > Not sure why you'd take that out when someone using UINTN for variables
> may
> > want to use MAX_UINTN ?    Future may be different.
>
> The UINTN type comes from the UEFI spec:
>
>     Unsigned value of native width. (4 bytes on supported 32-bit
>     processor instructions, 8 bytes on supported 64-bit processor
>     instructions, 16 bytes on supported 128-bit processor instructions)
>
> In this sense, "native" refers to the firmware execution environment.
> The firmware execution environment need not have anything in common with
> the build environment. (You can build 32-bit ARM firmware on X64 hosts.)
> In such a scenario, using UINTN *at all* is fraught with
> misunderstandings. It *would* be possible to use UINTN as it applies to
> the build (= hosted) environment, and in that sense MAX_UINTN would also
> be possible to define. However, the code being removed (= defining
> MAX_UINTN as MAX_ADDRESS) proves that that approach would be very easy
> to misunderstand and misuse. People could easily mistake it for applying
> to the firmware execution environment.
>
> UINT32 and UINT64 are not affected by this ambiguity.
>
> Optimally, given that the build utilities target a hosted C runtime,
> they should use standard C types, such as "unsigned int", or e.g.
> "uint32_t". Together with standard C macros expressing limits, such as
> UINT_MAX (from <limits.h>) and UINT32_MAX (from <stdint.h>).
>
> Clearly no-one has capacity to clean up BaseTools like this. For
> starters, we should at least remove whatever actively causes confusion.
>
> Thanks,
> Laszlo
>
> > On Mon, Dec 3, 2018 at 5:08 AM Laszlo Ersek <lersek@redhat.com> wrote:
> >
> >> On 11/30/18 23:45, Ard Biesheuvel wrote:
> >>> The maximum value that can be represented by the native word size
> >>> of the *target* should be irrelevant when compiling tools that
> >>> run on the build *host*. So drop the definition of MAX_UINTN, now
> >>> that we no longer use it.
> >>>
> >>> Contributed-under: TianoCore Contribution Agreement 1.1
> >>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> >>> Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
> >>> ---
> >>>  BaseTools/Source/C/Common/CommonLib.h | 1 -
> >>>  1 file changed, 1 deletion(-)
> >>>
> >>> diff --git a/BaseTools/Source/C/Common/CommonLib.h
> >> b/BaseTools/Source/C/Common/CommonLib.h
> >>> index 6930d9227b87..b1c6c00a3478 100644
> >>> --- a/BaseTools/Source/C/Common/CommonLib.h
> >>> +++ b/BaseTools/Source/C/Common/CommonLib.h
> >>> @@ -22,7 +22,6 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND,
> >> EITHER EXPRESS OR IMPLIED.
> >>>
> >>>  #define MAX_LONG_FILE_PATH 500
> >>>
> >>> -#define MAX_UINTN MAX_ADDRESS
> >>>  #define MAX_UINT64 ((UINT64)0xFFFFFFFFFFFFFFFFULL)
> >>>  #define MAX_UINT16  ((UINT16)0xFFFF)
> >>>  #define MAX_UINT8   ((UINT8)0xFF)
> >>>
> >>
> >> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
> >> _______________________________________________
> >> edk2-devel mailing list
> >> edk2-devel@lists.01.org
> >> https://lists.01.org/mailman/listinfo/edk2-devel
> >>
> >
>
>