From mboxrd@z Thu Jan  1 00:00:00 1970
Subject: Re: [edk2-devel] [PATCH v3 0/4] ArmPkg/SecurityPkg: Fixes for ArmTrngLib/RngDxe
To: Ard Biesheuvel <ardb@kernel.org>,devel@edk2.groups.io
From: "Sami Mujawar" <sami.mujawar@arm.com>
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Date: Wed, 07 Dec 2022 00:53:18 -0800
References: <CAMj1kXG5c7C0R6Vsw6j0uYF7uY6FHFyVaGyfLu3zZ1MhuiSV_Q@mail.gmail.com>
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Hi Ard,
On Sat, Nov 26, 2022 at 06:34 AM, Ard Biesheuvel wrote:

>=20
> The remaining code still looks a bit clunky to me. Can't we just
> return an error from the library constructor of the library cannot
> initialize due to a missing prerequisite?

The problem with returning an error code from a library constructor is that=
 it generates an ASSERT for debug builds. The reason is that the generated =
code in AutoGen.c looks as shown below:

VOID
EFIAPI
ProcessLibraryConstructorList (
IN EFI_HANDLE=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 ImageHandle,
IN EFI_SYSTEM_TABLE=C2=A0 *SystemTable
)
{
EFI_STATUS=C2=A0 Status;

Status =3D HobLibConstructor (ImageHandle, SystemTable);
ASSERT_EFI_ERROR (Status);
...
Status =3D ArmTrngLibConstructor ();
ASSERT_RETURN_ERROR (Status);

}

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Hi Ard,<br />On Sat, Nov 26, 2022 at 06:34 AM, Ard Biesheuvel wrote:<br />
<blockquote>The remaining code still looks a bit clunky to me. Can't we jus=
t<br />return an error from the library constructor of the library cannot<b=
r />initialize due to a missing prerequisite?</blockquote>
The problem with returning an error code from a library constructor is that=
 it generates an ASSERT for debug builds. The reason is that the generated =
code in AutoGen.c looks as shown below:<br /><br />VOID<br />EFIAPI<br />Pr=
ocessLibraryConstructorList (<br />&nbsp; IN EFI_HANDLE&nbsp;&nbsp;&nbsp;&n=
bsp;&nbsp;&nbsp;&nbsp; ImageHandle,<br />&nbsp; IN EFI_SYSTEM_TABLE&nbsp; *=
SystemTable<br />&nbsp; )<br />{<br />&nbsp; EFI_STATUS&nbsp; Status;<br />=
<br />&nbsp; Status =3D HobLibConstructor (ImageHandle, SystemTable);<br />=
&nbsp; ASSERT_EFI_ERROR (Status);<br />...<br />&nbsp; Status =3D ArmTrngLi=
bConstructor ();<br />&nbsp; ASSERT_RETURN_ERROR (Status);<br /><br />}<br =
/><br />

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