Hi Russell,
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
What do you suggest?
Thanks!
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
