2017-06-13 12:01 GMT+08:00 Andrew Fish <af...@apple.com>: > >> On Jun 12, 2017, at 7:14 PM, Jun Nie <jun....@linaro.org> wrote: >> >> 2017-06-12 23:53 GMT+08:00 Leif Lindholm <leif.lindh...@linaro.org>: >>> On Mon, Jun 12, 2017 at 09:59:28AM +0800, Jun Nie wrote: >>>> Add alignment for ECSD data for DMA access. Otherwise >>>> the data is corrupted on Sanechips platform. >>> >>> I never did see a reply to my proposed solution, and the below is not >>> it. Can you explain why you prefer this one? >>> >>> / >>> Leif >> >> Sorry, just see your email because that thread is not highlighted for >> new email in gmail for unknown reason. >> I have concern that "UINT64 VENDOR_SPECIFIC_FIELD[8]" cannot secure >> the ECSD alignment because it is not the first member. Changing the >> first member to "UINT64 RESERVED_1[2]" shall secure the alignment. But >> I preferred Pad method. It is more readable if all ECSD member are >> UINT8 type. It is also more clear to add alignment info in CARD_INFO, >> just before ECSD member. >> I do not get point of Andrew, maybe he share the same concern. >> > > Jun > > typedef enum { > UNKNOWN_CARD, > MMC_CARD, //MMC card > MMC_CARD_HIGH, //MMC Card with High capacity > EMMC_CARD, //eMMC 4.41 card > SD_CARD, //SD 1.1 card > SD_CARD_2, //SD 2.0 or above standard card > SD_CARD_2_HIGH //SD 2.0 or above high capacity card > } CARD_TYPE; > > Per C spec sizeof(CARD_TYPE) can be 1, 2, 4, or 8 (64-bit integer), and it is > legal for the compiler to pick any of these. So it is not portable C code to > use an enum in a data structure when layout maters. > > Thanks, > > Andrew Fish
CARD_TYPE CardType is 2nd member of CARD_INFO, while ECSDData is the last member and I just want to align it to 8 bytes. I had assume pad will be added automatically by compiler if CARD_TYPE is not 8 bytes aligned and UNIT64 type appear in following member. Does enum will impact the later member alignment? Could you help elaborate more about this? Thank you! Jun >> >>> >>>> Contributed-under: TianoCore Contribution Agreement 1.0 >>>> Signed-off-by: Jun Nie <jun....@linaro.org> >>>> --- >>>> EmbeddedPkg/Universal/MmcDxe/Mmc.h | 1 + >>>> 1 file changed, 1 insertion(+) >>>> >>>> diff --git a/EmbeddedPkg/Universal/MmcDxe/Mmc.h >>>> b/EmbeddedPkg/Universal/MmcDxe/Mmc.h >>>> index 8a7d5a3..6e3ab17 100644 >>>> --- a/EmbeddedPkg/Universal/MmcDxe/Mmc.h >>>> +++ b/EmbeddedPkg/Universal/MmcDxe/Mmc.h >>>> @@ -319,6 +319,7 @@ typedef struct { >>>> OCR OCRData; >>>> CID CIDData; >>>> CSD CSDData; >>>> + UINT64 Pad; // For 8 bytes alignment of >>>> ECSDData >>>> ECSD ECSDData; // MMC V4 extended card >>>> specific >>>> } CARD_INFO; >>>> >>>> -- >>>> 1.9.1 >>>> >> _______________________________________________ >> edk2-devel mailing list >> edk2-devel@lists.01.org >> https://lists.01.org/mailman/listinfo/edk2-devel > _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel