From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Timur Tabi <timur@freescale.com>
Cc: linuxppc-dev@ozlabs.org, devicetree-discuss@lists.ozlabs.org
Subject: Re: [PATCH] powerpc: make the padding for the device tree a configurable option
Date: Thu, 20 May 2010 08:44:10 +1000 [thread overview]
Message-ID: <1274309050.1931.21.camel@pasglop> (raw)
In-Reply-To: <4BF4593E.8030101@freescale.com>
On Wed, 2010-05-19 at 16:33 -0500, Timur Tabi wrote:
> Benjamin Herrenschmidt wrote:
>
> >> So to accommodate future boards where more padding is needed, we make the
> >> option for the -p parameter configurable.
> >
> > Can't u-boot just allocate more space ?
>
> Yes and no. U-Boot has functions to increase the size of an fdt, but these
> functions can't be sure that the fdt will grow beyond its allocated space.
> So if U-Boot calls fdt_setprop() or fdt_add_subnode(), and there isn't
> enough space in the fdt, those functions will return with an error.
.../...
It's still not kernel business to have to deal with u-boot memory
allocation constraints. The padding in the kernel built is intended to
make space for DT changes done by the zImage wrapper.
Maybe we could add to libfdt a way to provide a realloc() callback to it
when it hits the max size, and uboot can then move things around (or
fail).
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
To: Timur Tabi <timur-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
Cc: linuxppc-dev-mnsaURCQ41sdnm+yROfE0A@public.gmane.org,
devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
Subject: Re: [PATCH] powerpc: make the padding for the device tree a configurable option
Date: Thu, 20 May 2010 08:44:10 +1000 [thread overview]
Message-ID: <1274309050.1931.21.camel@pasglop> (raw)
In-Reply-To: <4BF4593E.8030101-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
On Wed, 2010-05-19 at 16:33 -0500, Timur Tabi wrote:
> Benjamin Herrenschmidt wrote:
>
> >> So to accommodate future boards where more padding is needed, we make the
> >> option for the -p parameter configurable.
> >
> > Can't u-boot just allocate more space ?
>
> Yes and no. U-Boot has functions to increase the size of an fdt, but these
> functions can't be sure that the fdt will grow beyond its allocated space.
> So if U-Boot calls fdt_setprop() or fdt_add_subnode(), and there isn't
> enough space in the fdt, those functions will return with an error.
.../...
It's still not kernel business to have to deal with u-boot memory
allocation constraints. The padding in the kernel built is intended to
make space for DT changes done by the zImage wrapper.
Maybe we could add to libfdt a way to provide a realloc() callback to it
when it hits the max size, and uboot can then move things around (or
fail).
Ben.
next prev parent reply other threads:[~2010-05-19 22:44 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-19 19:53 [PATCH] powerpc: make the padding for the device tree a configurable option Timur Tabi
2010-05-19 19:53 ` Timur Tabi
2010-05-19 21:20 ` Benjamin Herrenschmidt
2010-05-19 21:20 ` Benjamin Herrenschmidt
2010-05-19 21:33 ` Timur Tabi
2010-05-19 21:33 ` Timur Tabi
2010-05-19 22:44 ` Benjamin Herrenschmidt [this message]
2010-05-19 22:44 ` Benjamin Herrenschmidt
2010-05-20 0:03 ` Timur Tabi
2010-05-20 0:03 ` Timur Tabi
2010-05-20 0:23 ` Benjamin Herrenschmidt
2010-05-20 0:23 ` Benjamin Herrenschmidt
2010-05-20 0:36 ` M. Warner Losh
2010-05-20 0:36 ` M. Warner Losh
2010-05-20 1:18 ` David Gibson
2010-05-20 1:18 ` David Gibson
2010-05-20 1:46 ` Timur Tabi
2010-05-20 1:46 ` Timur Tabi
2010-05-20 6:17 ` David Gibson
2010-05-20 6:17 ` David Gibson
2010-05-20 11:40 ` Timur Tabi
2010-05-20 11:40 ` Timur Tabi
2010-05-20 16:04 ` Scott Wood
2010-05-20 16:04 ` Scott Wood
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