Date: Sat, 14 Sep 2013 09:43:25 -0600 From: Ian Lepore <ian@FreeBSD.org> To: Nathan Whitehorn <nwhitehorn@FreeBSD.org> Cc: freebsd-arm@FreeBSD.org, freebsd-ppc@FreeBSD.org, freebsd-sparc64 <freebsd-sparc64@FreeBSD.org>, Marius Strobl <marius@alchemy.franken.de> Subject: Re: Patch for Cross-Reference Phandles Message-ID: <1379173405.1197.7.camel@revolution.hippie.lan> In-Reply-To: <52346D71.4080407@freebsd.org> References: <522CC7E0.9060508@freebsd.org> <5231D8A6.9080501@freebsd.org> <20130914133155.GA32845@alchemy.franken.de> <52346D71.4080407@freebsd.org>
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On Sat, 2013-09-14 at 09:06 -0500, Nathan Whitehorn wrote: > On 09/14/13 08:31, Marius Strobl wrote: > > On Thu, Sep 12, 2013 at 10:07:18AM -0500, Nathan Whitehorn wrote: > >> On 09/08/13 13:54, Nathan Whitehorn wrote: > >>> Open Firmware has three namespaces for handles: > >>> 1. Instance handles, for open devices > >>> 2. Package handles for the client interface > >>> 3. Package handles for device tree cross references > >>> > >>> On Powermac hardware, we assume that (2) and (3) are identical and > >>> call both phandles. On embedded FDT systems, you can't open devices > >>> and so we abuse ihandle_t for (3). IBM pSeries hardware, however, has > >>> all three things. With that in mind, I'd like to start separating > >>> them. The patch at > >>> http://people.freebsd.org/~nwhitehorn/xref_phandle.diff adds a new > >>> function (OF_child_xref_phandle) that takes a phandle of type (3) and > >>> turns into one of type (2) by searching for entries named "phandle", > >>> "ibm,phandle", or "linux,phandle" in the tree. This should work for > >>> FDT as well, but is not connected in the patch to anything actually > >>> FDT related. > >>> > >>> Comments would be appreciated. I'd like to get to get this as in as > >>> soon as possible (given the HEAD freeze) otherwise. > >>> -Nathan > >> Since I haven't heard anything, it shouldn't affect any existing > >> platforms or code, and it would be nice to have this interface available > >> in the 10.x series, I plan to ask re@ for commit approval tomorrow. > >> Please let me know if there are any objections. > > Technically that patch is fine. It would be nice if you could fix the > > style bugs before committing, though. In OF_child_xref_phandle(), the > > variables should go above the comment and you don't need to initialize > > the static global one in ofw_pcibus.c to zero explicitly. If you do > > nevertheless, spaces should go before and after the '='. > > > > Thanks! I think the explicit zero initialization adds some clarity for > people reading the code, so I'd like to keep it. The rest of the changes > have been made. > -Nathan The explicit zero init also makes it 4 bytes harder to fit the kernel into a small flash on embedded systems. We should be eliminating zero-inits that move items from bss to data, not adding new ones. -- Ian
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