From: Jacob Moody <moody@mail.posixcafe.org>
To: 9front@9front.org
Subject: Re: [9front] Re: [PATCH] game boy advance header target for 5l
Date: Fri, 3 Mar 2023 14:18:29 -0700 [thread overview]
Message-ID: <cc0b0481-8a24-3025-8fa3-7153a4207e55@posixcafe.org> (raw)
In-Reply-To: <859F297B22C45B7453E14CCF75E203C8@felloff.net>
On 3/3/23 13:59, cinap_lenrek@felloff.net wrote:
>> I dont want to do relocation, I just want to know
>> why external programs that only work under assumptions
>> of how the a.out was linked are preferable to just
>> having the linker output correct files.
>
> Sorry, then i must have misundersood you.
>
>> If everyone else is in agreement that this kind of header
>> code should only be done in external programs, should that
>> code also be moved to be external or deleted?
>
> I do not see a need to be dogmatic about this at all
> or force a decision.
>
> I do not have any skin in this game nor do i have a gameboy.
>
> Was just pointing out why an external tool would only solve
> half the problem in this case. But i think we agree here.
>
> A external tool made perfect sense for uimage as we want to
> generate both an a.out (for debugger and /dev/reboot) and a
> uimage for uboot. Linking is quite expensive compared to just
> writing out a header and copying some data out of a file and
> calculating a checksum.
>
> For the gameboy rom image problem, my first guess would be to
> just generate the header using the assembler and pass that
> as the first object to the linker and have the linker geneate
> headerless image.
I ended up writing an aout2gba that does work as intended. I think
this may still be quite useful, I am considering teaching games/gba
how to load a gba a.out file (for debug info), so being able to
generate both may be useful.
In porting a more complicated rom, I realized that plan9 specific
init code is unavoidable anyway due to needing to setup R12:
MOVW $setR12(SB), R12 /* load the SB */
Somehow I had missed that this preamble would be needed. Given that
we need an l.s entrypoint for this anyway, I can just stuff the header
in there and encode the entry point manually to just jump down after the
header as we discussed. I am working on a /sys/src/cmd/mkone equivalent
and some plumbing, I'll post another diff soon.
Thanks,
moody
next prev parent reply other threads:[~2023-03-03 21:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-02 6:56 [9front] " Jacob Moody
2023-03-02 11:15 ` [9front] " Anthony Martin
2023-03-02 16:08 ` Jacob Moody
2023-03-02 17:33 ` cinap_lenrek
2023-03-02 17:50 ` Jacob Moody
2023-03-03 20:59 ` cinap_lenrek
2023-03-03 21:18 ` Jacob Moody [this message]
2023-03-04 15:53 ` cinap_lenrek
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