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Re: RFC: ABI support for special memory area
Here is the my current proposal.
ABI support for special memory area
To section attributes, add
#define SHF_GNU_MBIND 0x00100000
for sections used to place data or text into a special memory area.
The section names should start with ".mbind" so that they won't be
grouped together with normal sections by link editor. The sh_info
field indicates the special memory type. SHF_GNU_MBIND is only
applicable to SHF_ALLOC sections.
To the "Program Header" section, add an inclusive range of segment types
for GNU_MBIND segments:
#define PT_GNU_MBIND_NUM 4096
#define PT_GNU_MBIND_LO (PT_LOOS + 0x474e555)
#define PT_GNU_MBIND_HI (PT_GNU_MBIND_LO + PT_GNU_MBIND_NUM - 1)
The array element specifies the location and size of a special memory area.
Each GNU_MBIND segment contains one GNU_MBIND section and the segment
type is PT_GNU_MBIND_LO plus the sh_info value. If the sh_info value is
greater than PT_GNU_MBIND_NUM, no GNU_MBIND segment will be created. Each
GNU_MBIND segment must be aligned at page boundary. The interpretation of
the special memory area information is implementation-dependent.
Implementations may ignore GNU_MBIND segment.
int __gnu_mbind_setup (unsigned int type, void *addr, size_t length);
It sets up special memory area of 'type' and 'length' at 'addr' where
'addr' is a multiple of page size. It returns zero for success, positive
value of ERRNO for non-fatal error and negative value of ERRNO for fatal
After all shared objects and the executable file are loaded, relocations
are processed, for each GNU_MBIND segment in a shared object or the
executable file, run-time loader calls __gnu_mbind_setup with type,
address and length. The default implementation of __gnu_mbind_setup is
__gnu_mbind_setup (unsigned int type, void *addr, size_t length)
which can be overridden by a different implementation at link-time.