On 2/14/19 3:46 AM, Normand wrote:
On 14/02/2019 11:10, Florian Weimer wrote:
* Normand:
With new gcc9 there are new error reported by
-Werror=address-of-packed-member
How to handle such error ?
eg:
libflash/ecc.c:419:24: error: taking address of packed member of
'struct ecc64' may result in an unaligned pointer value
[-Werror=address-of-packed-member]
419 | memcpy(inc_uint64_by(&ecc_word.data, alignment), src,
bytes_wanted);
| ^~~~~~~~~~~~~~
Isn't the problem here that the address of the unaligned ecc_word.data
is being passed to inc_uint64_by() declared to take a pointer to
a naturally aligned uint64_t:
static uint64_t *inc_uint64_by(const uint64_t *p, uint64_t i)
{
return (uint64_t *)(((char *)p) + i);
}
If the purpose of inc_uint64_by() is to align a pointer to a misaligned
integer (or something like that) then declaring it to take an argument
of that type should avoid the warning. E.g., like so:
typedef uint64_t unaligned_uint64_t __attribute__ ((aligned (1)));
static uint64_t* inc_uint64_by (const unaligned_uint64_t *p, uint64_t i)
{
return (uint64_t *)(((char *)p) + i);
}
(I'm just guessing here. I have no idea if this is what the function
does, or if the return type should also be unaligned_int64_t.)
Martin
What does the definition of struct ecc64 look like?
Thanks,
Florian
Florian, the related struct is:
struct ecc64 {
beint64_t data;
uint8_t ecc;
} __attribute__((__packed__));
as per header file from:
https://github.com/open-power/skiboot/blob/skiboot-6.2.x/libflash/ecc.h#L25
