Re: MPS: Loaded pdump

["Gerd Möllmann" <gerd.moellmann@gmail.com>]

Gerd Möllmann <gerd.moellmann@gmail.com> writes:

> Helmut Eller <eller.helmut@gmail.com> writes:
>
>> On Thu, May 09 2024, Gerd Möllmann wrote:
>>
>>> Helmut Eller <eller.helmut@gmail.com> writes:
>>>
>>>> On Thu, May 09 2024, Gerd Möllmann wrote:
>>>>
>>>>> - The root is unstructured. We can't scan exactly, and so can't do
>>>>>   anything special for pointers to non-MPS memory that Lisp objects
>>>>>   have. This leads to some horrible workarounds.
>>>>
>>>> The pdumper could put the different types (cons, symbol, string,
>>>> vectorlike) in different sections.  Then we could probably scan it
>>>> exactly.
>>>
>>> Either that, or we could dump the igc_header with the objects. Don't
>>> know how difficult that would be. My gut tells me introducing more
>>> sections than the 3 we have could be more work.
>>
>> Had forgotten about that; with the additional advantage that the
>> existing scan code would work right away.
>
> But this looks also interesting
>
>   struct dump_header
>   {
>     ...
>     /* "Relocation" table we abuse to hold information about the
>        location and type of each lisp object in the dump.  We need for
>        pdumper_object_type and ultimately for conservative GC
>        correctness.  */
>     struct dump_table_locator object_starts;
>
> I think I'll read the pdumper code a bit more in the next days.

Scratch that. A bit of LSP, and one can see it's not why I thought it
was. It doesn't always have the informaton what kind of Lisp object is
somewhere in the dump. AFAIU, it is for conservatice marking to be able
to tell the GC if a reference is to an object star or not.