Hi Russell,
On Wed, Nov 13, 2019 at 6:04 PM Russell King - ARM Linux admin
<linux@xxxxxxxxxxxxxxx> wrote:
> On Wed, Nov 13, 2019 at 02:32:19PM +0100, Geert Uytterhoeven wrote:
> > On Wed, Nov 13, 2019 at 11:39 AM Russell King - ARM Linux admin
> > <linux@xxxxxxxxxxxxxxx> wrote:
> > > On Wed, Nov 13, 2019 at 11:27:29AM +0100, Geert Uytterhoeven wrote:
> > > > The RZA2MEVB sub board has 64 MiB of SDRAM at 0x0C000000 (CS3 space).
> > > > Hence the mask for CONFIG_AUTO_ZRELADDR needs to be changed, otherwise
> > > > the system will crash because it will try to decompress a zImage or
> > > > uImage to a non-RAM garbage address.
> > > >
> > > > Based on a patch in the BSP by Chris Brandt <chris.brandt@xxxxxxxxxxx>.
> > > >
> > > > Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> > > > ---
> > > > No idea what to do with the rest of the comment, or if this breaks
> > > > existing platforms.
> > >
> > > We occasionally have discussions about this - the last one was a big
> > > one in Edinburgh, and the answer is we can't change this in mainline.
> > > They've also come up on the mailing lists as well.
> > >
> > > I'm not going to rehash this old argument yet again - the comment
> > > details the reason for it, and is there to prevent exactly this.
> >
> > Sorry, I wasn't aware of that discussion.
> > I had a chat about this at ELC-E with Arnd, and he was open to this change.
> >
> > > If someone is silly enough to come up with a platform that violates
> > > the documented 32-bit ARM booting protocol, then they can't expect
> > > the kernel to bend to their platform's requirements at the expense of
> > > already merged platforms.
> >
> > Documentation/arm/booting.rst:
> > 1. The kernel should be placed in the first 128MiB of RAM: check.
> > 2. A safe location is just above the 128MiB boundary from start of RAM:
> > oops. Not all platforms have more than 128 MiB of RAM...
> >
> > An alternative is to fall to the builtin 4 MiB of SRAM, or the 8 MiB of
> > HyperRAM on RZA2MEVB, but doing that requires using XIP.
> > Which brings us to your response in the other email:
> >
> > > Are we going back to non-multi-platform kernels? ;)
> >
> > Good question! ;-)
> >
> > 1. CONFIG_AUTO_ZRELADDR=n
> > 2. CONFIG_XIP_KERNEL=y
>
> If you're using an XIP kernel, you are by definition not using the
> decompressor.
Sure. I mean we may need 3 different setups for RZ/A:
1. multiplatform,
2. CONFIG_AUTO_ZRELADDR=n,
3. CONFIG_XIP_KERNEL=y.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
