Serial recovery compatibility with IAR toolchain

[stindaNXP]

Hi
There are several issues when an user try to compile serial recovery feature with IAR toolchain.
First one is in boot_serial_priv.h

struct nmgr_hdr {
#if (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
    uint8_t  _res1:3;
    uint8_t  nh_version:2;
    uint8_t  nh_op:3;		/* NMGR_OP_XXX */
#else
    uint8_t  nh_op:3;		/* NMGR_OP_XXX */
    uint8_t  nh_version:2;
    uint8_t  _res1:3;
#endif
    uint8_t  nh_flags;
    uint16_t nh_len;            /* length of the payload */
    uint16_t nh_group;          /* NMGR_GROUP_XXX */
    uint8_t  nh_seq;            /* sequence number */
    uint8_t  nh_id;             /* message ID within group */
} __packed;

IAR doesn't define __BYTE_ORDER__ and __ORDER_BIG_ENDIAN__ so equation is evaluated as 0 == 0 which leads to the structure handled as big endian. I assume the Zephyr has adaptation code what handles this situation, however for bare-metal use case this should be fixed.

Second problem is with attribute __packed. Similar issue was fixed for image.h in this PR.

I have fixed on my side with this approach

#if defined(__IAR_SYSTEMS_ICC__)

#define STRUCT_PACKED __packed struct
#define __ORDER_BIG_ENDIAN__    1
#define __ORDER_LITTLE_ENDIAN__ 2
#if defined(__LITTLE_ENDIAN__)
#if __LITTLE_ENDIAN__ == 1
#define __BYTE_ORDER__          __ORDER_LITTLE_ENDIAN__
#else
#define __BYTE_ORDER__          __ORDER_BIG_ENDIAN__
#endif /* __LITTLE_ENDIAN__ == 1 */
#endif

#elif defined(__GNUC__)

#define STRUCT_PACKED struct __attribute__((__packed__))

#else
#error "Unknown toolchain"
#endif

STRUCT_PACKED nmgr_hdr {
#if (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
    uint8_t  _res1:3;
    uint8_t  nh_version:2;
    uint8_t  nh_op:3;		/* NMGR_OP_XXX */
#else
    uint8_t  nh_op:3;		/* NMGR_OP_XXX */
    uint8_t  nh_version:2;
    uint8_t  _res1:3;
#endif
    uint8_t  nh_flags;
    uint16_t nh_len;            /* length of the payload */
    uint16_t nh_group;          /* NMGR_GROUP_XXX */
    uint8_t  nh_seq;            /* sequence number */
    uint8_t  nh_id;             /* message ID within group */
};

Third problem are defines EINVAL, EBADMSG, EADDRINUSE and ENOMSG across the serial recovery code. This is also unknown to IAR as errno.h doesn't define those.

[d3zd3z]

errno.h is generally part of the C library, not the C compiler, so I'm not sure what IAR is providing. Are you building with Zephyr, or standalone?

As far as the endianness macros, those are not consistent across compilers, and will generally need to be provided by project ifdefs that determine it based on knowledge of the toolchain. Zephyr should have some of these, but let me know if you are building on Zephyr, or another backend.

[stindaNXP]

I am building standalone using IAR 9.60.4.
I assume these defines and endianness macros come from zephyr sdk somewhere.

[d3zd3z]

This might be useful from mbedtls:

#if !defined(__BYTE_ORDER__)

#if defined(__LITTLE_ENDIAN__)
/* IAR defines __xxx_ENDIAN__, but not __BYTE_ORDER__ */
#define MBEDTLS_IS_BIG_ENDIAN 0
#elif defined(__BIG_ENDIAN__)
#define MBEDTLS_IS_BIG_ENDIAN 1
#else
static const uint16_t mbedtls_byte_order_detector = { 0x100 };
#define MBEDTLS_IS_BIG_ENDIAN (*((unsigned char *) (&mbedtls_byte_order_detector)) == 0x01)
#endif

#else

#if (__BYTE_ORDER__) == (__ORDER_BIG_ENDIAN__)
#define MBEDTLS_IS_BIG_ENDIAN 1
#else
#define MBEDTLS_IS_BIG_ENDIAN 0
#endif

#endif /* !defined(__BYTE_ORDER__) */

[d3zd3z]

The errno in zephyr comes from picolibc. You are probably best just defining them yourself. I'd be curious where the definitions are getting used, because I'm not sure what would be returning them if your SDK doesn't see them defined.

[stindaNXP]

Thank you for answers.
Could you atleast fix the packed attribute? This is similar to #2126