Re: rtl metadata musings

[Ludovic Courtès]

Andy Wingo <address@hidden> skribis:

> On Sun 19 May 2013 23:52, address@hidden (Ludovic Courtès) writes:
>
>> I guess literal strings would go out as per ‘SCM_IMMUTABLE_STRING’
>> (which needs relocation), right?
>
> Yep.  Right now the stringbuf goes into read-only memory, but the string
> itself goes in writable memory as it needs its link to the stringbuf
> fixed up (relocated) at runtime.

OK.  It could be in a PT_GNU_RELRO segment, which the loader (well, the
other one, from glibc ;-)) remaps read-only after relocation.

[A moment of enlightenment when one realizes what it means to have our
own ELF toolchain.  :-)]

>> Perhaps the .guile.docstr section could eventually be used to contain
>> stexi, but that seems to already fit into the plan anyway.
>
> That can happen already, but I think if we do texinfo we should
> serialize the string as texinfo -- that way no relocs are needed if
> docstrings aren't used, because if we use the .docstr string table, it's
> just an offset into the image of a NUL-terminated UTF-8 byte sequence.

Right, makes sense.

> (I suppose we should be careful about embedded NUL characters; perhaps
> we should use some other format for the string tables.)

NULs in string contents should not be a problem, as long as there’s
info somewhere about the string length, no?

UTF-8-encoded ELF symbols may be more of a problem.  How could NULs in
symbols be handled?

Thanks,
Ludo’.