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Re: RISC-V support
- From: Kurt Roeckx <kurt at roeckx dot be>
- To: Mark Wielaard <mark at klomp dot org>
- Cc: Jim Wilson <jimw at sifive dot com>, elfutils-devel at sourceware dot org, Karsten Merker <merker at debian dot org>
- Date: Sat, 12 Jan 2019 00:23:32 +0100
- Subject: Re: RISC-V support
- References: <CAFyWVaa3aixXz2zUN_aBSC9=CpkOXNPxCiun1MP-htghRqqwuw@mail.gmail.com> <firstname.lastname@example.org>
On Tue, Jan 08, 2019 at 02:52:33PM +0100, Mark Wielaard wrote:
> > There is a problem here though. The riscv support was written to try
> > to handle both 32-bit and 64-bit targets with a single elfutils
> > backend. But I have 6 ABIs I need to (theoretically) handle in
> > riscv_retval.c. The return_value_location function doesn't take any
> > ebl or elf pointer, so I can't handle it there. I can handle it in
> > riscv_init.c by checking ebl and elf pointers there, and calling an
> > appropriate function, but I'm not sure if that is OK. Currently,
> > none
> > of the *_init.c files are using the elf pointer argument.
> The ppc64 init does (to lookup the odp table which is necessary for
> ppc64[be], but not ppc64le). It is allowed. And the backends/ebl
> interface is completely internal, so feel free to suggest changes if
> they make sense for riscv. If it is necessary we'll just update the
> other backends.
I've been looking at mips, and it seems to have many different
ABIs too. A patch I've received does this:
mips_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
/* First find the ABI used by the elf object */
enum mips_abi abi = find_mips_abi(functypedie->cu->dbg->elf);
The patch only supports 6 ABIs, but I think there are really over
Maybe it would be good that we only need to determine the ABI
once, instead of each time the function is called.