Date: Thu, 14 Feb 2013 07:40:31 -0700 From: Warner Losh <imp@bsdimp.com> To: Robert Watson <rwatson@FreeBSD.org> Cc: "freebsd-arch@FreeBSD.org Arch" <freebsd-arch@freebsd.org>, Marcel Moolenaar <marcel@xcllnt.net> Subject: Re: FDT on x86 and for non-fdtbus devices. Message-ID: <8606E19D-98A2-4E2C-A9E3-5056C1BAC34E@bsdimp.com> In-Reply-To: <alpine.BSF.2.00.1302141031480.65091@fledge.watson.org> References: <03A622DA-EFD4-4984-8FC3-CD8B4832C32E@xcllnt.net> <alpine.BSF.2.00.1302141031480.65091@fledge.watson.org>
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On Feb 14, 2013, at 3:33 AM, Robert Watson wrote: >=20 > On Wed, 13 Feb 2013, Marcel Moolenaar wrote: >=20 >> I think one way to state the problem in a generic way is: How can we = obtain the FDT pnode_t given an arbitrary device_t and use the pnode_t = to query for properties, etc. >>=20 >> Are people already doing things like this? Is there an interest in = being able to do things like this? Are changes to drivers to have them = query FDT contributable at all or do people think such would be = "pollution"? >=20 > Only loosely related, but another thing we'd like to be able to do at = SRI/Cambridge is merge ROM-discovered FDT configuration data with = kernel-linked configuration data. For example, we'd like to rely on the = device's ROM for a list of physical device layouts and so on, but embed = our description of flash layout, additional device driver configuration = information (e.g., /dev node information for avgen, which exports = devices unsupported by specific device drivers using a generic = memory-mapped interface), etc, in the compiled kernel for the device. = I'm not sure if that's something that's of interest in this context as = well? IF you want to just add nodes to the FDT, I think that having a merge = function in ubldr and such wouldn't be too horribly hard. If you wanted = to change leaf nodes already in the tree, that would be quite a bit = harder, but might be doable in the kernel context.... But I'm curious why your specific example wouldn't already live in the = FDT for your board.... Warner
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