Re: [PATCH 1/2] EmbeddedPkg/PrePiMemoryAllocationLib: Added AllocateZeroPool()

[Jeff Brasen <jbrasen@nvidia.com>]

________________________________
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Sent: Thursday, November 8, 2018 4:13 AM
To: Jeff Brasen; Leif Lindholm
Cc: edk2-devel@lists.01.org
Subject: Re: [edk2] [PATCH 1/2] EmbeddedPkg/PrePiMemoryAllocationLib: Added AllocateZeroPool()

On 30 October 2018 at 22:30, Jeff Brasen <jbrasen@nvidia.com> wrote:
> This function is exposed by the MemoryAllocationLib header.
> An AllocateZeroPool() function has been added to fix modules depending on
> this library and this function.
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jeff Brasen <jbrasen@nvidia.com>
> ---
>  .../PrePiMemoryAllocationLib/MemoryAllocationLib.c | 32 ++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
>
> diff --git a/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c b/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c
> index 0e75e23..f93f9cf 100644
> --- a/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c
> +++ b/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c
> @@ -16,6 +16,7 @@
>  #include <PiPei.h>
>
>  #include <Library/BaseLib.h>
> +#include <Library/BaseMemoryLib.h>
>  #include <Library/PrePiLib.h>
>  #include <Library/DebugLib.h>
>
> @@ -195,6 +196,37 @@ AllocatePool (
>  }
>
>  /**
> +  Allocates and zeros a buffer of type EfiBootServicesData.
> +
> +  Allocates the number bytes specified by AllocationSize of type EfiBootServicesData, clears the
> +  buffer with zeros, and returns a pointer to the allocated buffer.  If AllocationSize is 0, then a
> +  valid buffer of 0 size is returned.

I guess this is just boilerplate, but what on earth is 'a valid buffer
of 0 size'?

[JB] Copied this from the MemoryAllocationLib but allocate with create creates a free-able buffer is created with a unique pointer but you can't read/write to it (as it has no .

>  If there is not enough memory remaining to satisfy the
> +  request, then NULL is returned.
> +
> +  @param  AllocationSize        The number of bytes to allocate and zero.
> +
> +  @return A pointer to the allocated buffer or NULL if allocation fails.
> +
> +**/
> +VOID *
> +EFIAPI
> +AllocateZeroPool (
> +  IN UINTN  AllocationSize
> +  )
> +{
> +  VOID *Buffer;
> +
> +  Buffer = AllocatePool (AllocationSize);
> +  if (NULL == Buffer) {

Please don't use Yoda speak

[JB] Will update, habit of mine from before compilers would generally report a warning for assignments in if statements.

> +    return NULL;
> +  }
> +
> +  SetMem (Buffer, AllocationSize, 0);
> +
> +  return Buffer;
> +}
> +
> +/**
>    Frees a buffer that was previously allocated with one of the pool allocation functions in the
>    Memory Allocation Library.
>
> --
> 2.7.4
>
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> edk2-devel@lists.01.org
> https://lists.01.org/mailman/listinfo/edk2-devel


Thanks,

Jeff


Thanks,

Jeff

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