Date: Sat, 30 Jul 2022 21:12:18 -0700 From: Kyle Evans <kevans@freebsd.org> To: Obsto Clades <obsto.clades@zohomail.com> Cc: hackers@freebsd.org Subject: Re: lua loader Message-ID: <CACNAnaEPwNv9bBWjHyMZ-bS=Y0jGi8dthvyxiBg0e-wRTc0uJw@mail.gmail.com> In-Reply-To: <5a874623-76e4-7fd6-2e81-2aed51f07cbd@zohomail.com> References: <F50628CB-1100-4EB6-8682-4B42B1B15800@chrisbowman.com> <5a874623-76e4-7fd6-2e81-2aed51f07cbd@zohomail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Fri, Jul 29, 2022 at 6:06 PM Obsto Clades <obsto.clades@zohomail.com> wrote: > > On 7/29/22 14:26, Christopher Bowman wrote: > > I’ve been looking through the lua code in /boot/loader/lua I can’t really say I understand how the FDT gets loaded or even find the code that does but I am able to load a DTB using: > > > > load -t dtb /boot/dtb/foo.dtb > > > > It doesn’t see that overlays are supported (at least in the lua loader). I have a fdt_overlay=“overlay.dtb” statement in my loader.conf but I don’t see it being honored. > > Am I correct in understanding that? > > > > If I’m not correct could someone point me at the code that does the overlay loading so I could look at it? > > Thanks > > Christopher > > > I am also interesting in learning more about the lua loader. So, if > anybody replies to Christopher's question, could you please include me > in your replies. > Hey, I ended up reaching out to Christopher out-of-band (IRC) after identifying them from a question they had asked a couple days ago. The answer to this particular question is that fdt_overlays doesn't require any real interpreter support -- it's all implemented in C (see: stand/fdt/fdt_loader_cmd.c; I had gotten the path wrong both in IRC and another e-mail I sent not too long ago. D'oh!). The interpreted scripts will read loader.conf and stuff (most) of the contents into the loader environment, which is how the C part understands that it needs to apply some overlay(s). A couple of different actions will trigger overlay application; it should happen automatically at or maybe a little after loadelf (lualoader's term for it) but before jumping to the kernel, or you can drop to the loader prompt and trigger it manually by trying to inspect the loaded FDT with the fdt command. Thanks, Kyle Evans
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CACNAnaEPwNv9bBWjHyMZ-bS=Y0jGi8dthvyxiBg0e-wRTc0uJw>