[PATCH, V2 4/9] include: sframe: doc: define new flag SFRAME_F_FDE_FUNC_START_ADDR_PCREL

[Jan Beulich]

On 07.06.2025 07:37, Indu Bhagat wrote:
> On 6/6/25 3:00 AM, Jan Beulich wrote:
>> On 04.06.2025 09:08, Indu Bhagat via Binutils wrote:
>>> --- a/libsframe/sframe.c
>>> +++ b/libsframe/sframe.c
>>> @@ -205,7 +205,8 @@ flip_fde (sframe_func_desc_entry *fdep)
>>>   static bool
>>>   sframe_header_sanity_check_p (sframe_header *hp)
>>>   {
>>> -  unsigned char all_flags = SFRAME_F_FDE_SORTED | SFRAME_F_FRAME_POINTER;
>>> +  uint8_t all_flags = (SFRAME_F_FDE_SORTED | SFRAME_F_FRAME_POINTER
>>> +               | SFRAME_F_FDE_FUNC_START_ADDR_PCREL);
>>
>> Why the switch to uint8_t? From an abstract pov, unsigned char will be
>> available everywhere. Whether uint8_t exists is in principle uncertain;
>> none of the uint<N>_t are required to be provided. They may, aiui, in
>> particular be absent on architectures where (in binutils) we end up with
>> OCTETS_PER_BYTE != 1 (TI C4x / C54x). IOW using basic types is generally
>> preferable, wherever possible.
>>
> 
> RE: why switch to uint8_t. The data type used in the format specification for flags is uint8_t.
> 
> Elsewhere in bfd/elf-sframe.c too, the code also uses uint8_t for flags/version. So this was for consistency sake ATM: make sure to use uint8_t for flags.
> 
> There is the commit 6b258591644cf1db97113cc00f5373135d8755ba which makes me think that uin8_t being available is relied on by other components too; perhaps I am missing something.  In any case, if more flags are added, and OCTETS_PER_BYTE != 1, its more correct to use uint8_t, no?

I fear I can't answer this question, as - just to repeat - my understanding
is that on an arch where (when it's that target of a binutils build) we'd
set OCTETS_PER_BYTE to greater than 1, there's not going to be uint8_t. I
simply don't see how it could be defined there, fulfilling the requirements
of the standard. (By implication, my understanding is that for such targets
only cross builds of binutils are presently possible.)

Jan