[Libre-soc-bugs] [Bug 982] Support PowerPC ABI in ISACaller

[bugzilla-daemon at libre-soc.org]

https://bugs.libre-soc.org/show_bug.cgi?id=982

--- Comment #71 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
(In reply to Jacob Lifshay from comment #67)

>         if not self.is_svp64_mode and asmop == "sc" and
> self.syscall_emulation:
>             yield from self.emulate_syscall()
>             self.update_pc_next()
>             return

this is the preferred method, where emulate_syscall() is
about... 10-15 lines of code covering *every* syscall,
because the mmap'd area is in the exact same memory location as
where the ELF relocation targetted it.

(plus mmap and malloc/free redirect/replacement)

(with an option to specify what that is, on the command-line)

(In reply to Jacob Lifshay from comment #68)

>     def emulate_syscall(self):
>         syscall_num = self.gpr(0)
>         if syscall_num in self.syscall_table:
>             yield from self.syscall_table[syscall_num](self)
>         else:
>             self.cr.crl[0][CRFields.SO] = 1
>             self.gpr[3] = ENOSYS

this is the "last resort" method that actually is in some
ways "better", because by literally implementing every single
POSIX (ok ok i know Dmitry, it's not actually POSIX) call
we have no "hacks" - just a hell of a lot of work ahead instead.

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