Andrew, Thanks. I did not realize this was a struct with a single flexible array member. I agree that does not make sense.
The top level struct here is a HOB that must be in contiguous memory. The HOB can vary in size based on MicrocodeCount and StorageType. We are trying to make it easy to write the C code that produces and consumes this HOB. Using flexible array members helps improve the readability when structures have this attribute. For the storage type defined, the StorageContext is a single UINT64 value. Other storage type GUIDs may have more complex StorageContext structures. This array of structures is guaranteed to start on an 8-byte boundary, so the use case is to cast the start of the StorageContext to the defined type and access the array if structures and their fields. Do you have any suggestions on how to make this better? Mike > -----Original Message----- > From: af...@apple.com <af...@apple.com> > Sent: Thursday, February 27, 2020 7:43 AM > To: devel@edk2.groups.io; Kinney, Michael D > <michael.d.kin...@intel.com> > Cc: Gao, Liming <liming....@intel.com>; Fu, Siyuan > <siyuan...@intel.com>; Ni, Ray <ray...@intel.com>; > Chaganty, Rangasai V <rangasai.v.chaga...@intel.com> > Subject: Re: [edk2-devel] [Patch] > IntelSiliconPkg/ShadowMicrocodePei: Fix GCC build > error. > > Mike, > > Flexible array members must be the last element of a > struct but they can not be the only element. > > This is non standard behavior from the compilers that > are not throwing the error. > > Why not just use a pointer? > > Sent from my iPhone > > > On Feb 26, 2020, at 10:03 PM, Michael D Kinney > <michael.d.kin...@intel.com> wrote: > > > > Liming, > > > > This does not make sense. Those compilers > > should support C99 flexible array members. > > > > Structured PCDs also require use of flexible > > array members. > > > > We need to make sure the compiler flags for > > those tool chain are correct to support flexible > > array members. > > > > Mike > > > >> -----Original Message----- > >> From: Gao, Liming <liming....@intel.com> > >> Sent: Wednesday, February 26, 2020 9:58 PM > >> To: devel@edk2.groups.io; Kinney, Michael D > >> <michael.d.kin...@intel.com>; Fu, Siyuan > >> <siyuan...@intel.com> > >> Cc: Ni, Ray <ray...@intel.com>; Chaganty, Rangasai V > >> <rangasai.v.chaga...@intel.com> > >> Subject: RE: [edk2-devel] [Patch] > >> IntelSiliconPkg/ShadowMicrocodePei: Fix GCC build > >> error. > >> > >> Mike: > >> I find this issue on GCC5 tool chain tag with GCC > 5.5 > >> and CLANGPDB tool chain tag with CLANG 9.0.0 > >> > >> Thanks > >> Liming > >>> -----Original Message----- > >>> From: devel@edk2.groups.io <devel@edk2.groups.io> > On > >> Behalf Of Michael D Kinney > >>> Sent: Thursday, February 27, 2020 1:54 PM > >>> To: Gao, Liming <liming....@intel.com>; > >> devel@edk2.groups.io; Fu, Siyuan > <siyuan...@intel.com>; > >> Kinney, Michael D > >>> <michael.d.kin...@intel.com> > >>> Cc: Ni, Ray <ray...@intel.com>; Chaganty, Rangasai > V > >> <rangasai.v.chaga...@intel.com> > >>> Subject: Re: [edk2-devel] [Patch] > >> IntelSiliconPkg/ShadowMicrocodePei: Fix GCC build > >> error. > >>> > >>> Which GCC and CLANG tool chain tags? > >>> > >>> Flexible array member is a standard C feature > >>> documented in C99. > >>> > >>> Mike > >>> > >>>> -----Original Message----- > >>>> From: Gao, Liming <liming....@intel.com> > >>>> Sent: Wednesday, February 26, 2020 9:38 PM > >>>> To: Kinney, Michael D > <michael.d.kin...@intel.com>; > >>>> devel@edk2.groups.io; Fu, Siyuan > >> <siyuan...@intel.com> > >>>> Cc: Ni, Ray <ray...@intel.com>; Chaganty, Rangasai > >> V > >>>> <rangasai.v.chaga...@intel.com> > >>>> Subject: RE: [edk2-devel] [Patch] > >>>> IntelSiliconPkg/ShadowMicrocodePei: Fix GCC build > >>>> error. > >>>> > >>>> Mike: > >>>> I find GCC and CLANG will report the error for > >> the > >>>> empty struct. > >>>> > >>>> d:\allpkg\edk2- > >>>> > >> > platforms\Silicon\Intel\IntelSiliconPkg\Include\Guid/Mi > >>>> crocodeShadowInfoHob.h:61:11: error: flexible > array > >>>> member 'MicrocodeAddressInFlash' not allowed in > >>>> otherwise empty struct > >>>> UINT64 MicrocodeAddressInFlash[]; > >>>> ^ > >>>> 1 error generated. > >>>> > >>>> Thanks > >>>> Liming > >>>>> -----Original Message----- > >>>>> From: Kinney, Michael D > >> <michael.d.kin...@intel.com> > >>>>> Sent: Thursday, February 27, 2020 1:25 PM > >>>>> To: devel@edk2.groups.io; Fu, Siyuan > >>>> <siyuan...@intel.com>; Kinney, Michael D > >>>> <michael.d.kin...@intel.com> > >>>>> Cc: Ni, Ray <ray...@intel.com>; Chaganty, > >> Rangasai V > >>>> <rangasai.v.chaga...@intel.com>; Gao, Liming > >>>> <liming....@intel.com> > >>>>> Subject: RE: [edk2-devel] [Patch] > >>>> IntelSiliconPkg/ShadowMicrocodePei: Fix GCC build > >>>> error. > >>>>> > >>>>> What compiler does not like the flexible array > >>>>> member syntax []. > >>>>> > >>>>> Mike > >>>>> > >>>>>> -----Original Message----- > >>>>>> From: devel@edk2.groups.io > >> <devel@edk2.groups.io> > >>>> On > >>>>>> Behalf Of Siyuan, Fu > >>>>>> Sent: Wednesday, February 26, 2020 5:58 PM > >>>>>> To: devel@edk2.groups.io > >>>>>> Cc: Ni, Ray <ray...@intel.com>; Chaganty, > >> Rangasai > >>>> V > >>>>>> <rangasai.v.chaga...@intel.com>; Gao, Liming > >>>>>> <liming....@intel.com> > >>>>>> Subject: [edk2-devel] [Patch] > >>>>>> IntelSiliconPkg/ShadowMicrocodePei: Fix GCC > >> build > >>>>>> error. > >>>>>> > >>>>>> This patch fixes compiler error introduced by > >>>> commit > >>>>>> b0099a39bd. > >>>>>> > >>>>>> BZ: > >>>>>> > >>>> > >> > https://tianocore.acgmultimedia.com/show_bug.cgi?id=244 > >>>>>> 9 > >>>>>> Cc: Ray Ni <ray...@intel.com> > >>>>>> Cc: Rangasai V Chaganty > >>>> <rangasai.v.chaga...@intel.com> > >>>>>> Cc: Liming Gao <liming....@intel.com> > >>>>>> Signed-off-by: Siyuan Fu <siyuan...@intel.com> > >>>>>> --- > >>>>>> > >> .../Feature/ShadowMicrocode/ShadowMicrocodePei.c > >>>>>> | 2 +- > >>>>>> > >>>>>> > >>>> > >> > .../Intel/IntelSiliconPkg/Include/Guid/MicrocodeShadowI > >>>>>> nfoHob.h | 2 +- > >>>>>> 2 files changed, 2 insertions(+), 2 > >> deletions(-) > >>>>>> > >>>>>> diff --git > >>>>>> > >>>> > >> > a/Silicon/Intel/IntelSiliconPkg/Feature/ShadowMicrocode > >>>>>> /ShadowMicrocodePei.c > >>>>>> > >>>> > >> > b/Silicon/Intel/IntelSiliconPkg/Feature/ShadowMicrocode > >>>>>> /ShadowMicrocodePei.c > >>>>>> index 7e4084247e..8d6574f667 100644 > >>>>>> --- > >>>>>> > >>>> > >> > a/Silicon/Intel/IntelSiliconPkg/Feature/ShadowMicrocode > >>>>>> /ShadowMicrocodePei.c > >>>>>> +++ > >>>>>> > >>>> > >> > b/Silicon/Intel/IntelSiliconPkg/Feature/ShadowMicrocode > >>>>>> /ShadowMicrocodePei.c > >>>>>> @@ -247,7 +247,7 @@ ShadowMicrocodePatchWorker > >> ( > >>>>>> (VOID *) Patches[Index].Address, > >>>>>> Patches[Index].Size > >>>>>> ); > >>>>>> - MicrocodeAddressInMemory[Index] = (UINT64) > >>>> Walker; > >>>>>> + MicrocodeAddressInMemory[Index] = (UINT64) > >>>> (UINTN) > >>>>>> Walker; > >>>>>> Flashcontext- > >>> MicrocodeAddressInFlash[Index] > >>>> = > >>>>>> (UINT64) Patches[Index].Address; > >>>>>> Walker += Patches[Index].Size; > >>>>>> } > >>>>>> diff --git > >>>>>> > >>>> > >> > a/Silicon/Intel/IntelSiliconPkg/Include/Guid/MicrocodeS > >>>>>> hadowInfoHob.h > >>>>>> > >>>> > >> > b/Silicon/Intel/IntelSiliconPkg/Include/Guid/MicrocodeS > >>>>>> hadowInfoHob.h > >>>>>> index d887b39123..1daae1234a 100644 > >>>>>> --- > >>>>>> > >>>> > >> > a/Silicon/Intel/IntelSiliconPkg/Include/Guid/MicrocodeS > >>>>>> hadowInfoHob.h > >>>>>> +++ > >>>>>> > >>>> > >> > b/Silicon/Intel/IntelSiliconPkg/Include/Guid/MicrocodeS > >>>>>> hadowInfoHob.h > >>>>>> @@ -58,7 +58,7 @@ typedef struct { > >>>>>> // microcode patch address on flash. The > >> address > >>>> is > >>>>>> placed in same > >>>>>> // order as the microcode patches in > >>>>>> MicrocodeAddrInMemory. > >>>>>> // > >>>>>> - UINT64 MicrocodeAddressInFlash[]; > >>>>>> + UINT64 MicrocodeAddressInFlash[0]; > >>>>>> } EFI_MICROCODE_STORAGE_TYPE_FLASH_CONTEXT; > >>>>>> > >>>>>> #endif > >>>>>> -- > >>>>>> 2.19.1.windows.1 > >>>>>> > >>>>>> > >>>>>> > >>> > >>> > >>> > > > > > > > > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#55129): https://edk2.groups.io/g/devel/message/55129 Mute This Topic: https://groups.io/mt/71579115/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
