Hello, > From: Arnd Bergmann <arnd@xxxxxxxx> > Sent: 16 February 2020 20:38 > > On Sun, Feb 16, 2020 at 8:54 PM Chris Paterson > <Chris.Paterson2@xxxxxxxxxxx> wrote: > > > > Hello Arnd, Geert, > > > > > From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> > > > Sent: 16 February 2020 09:45 > > > To: Arnd Bergmann <arnd@xxxxxxxx> > > > > > > Hi Arnd, > > > > > > On Sat, Feb 15, 2020 at 5:59 PM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > > > On Sat, Feb 15, 2020 at 12:25 PM Geert Uytterhoeven > > > > <geert@xxxxxxxxxxxxxx> wrote: > > > > > On Thu, Feb 13, 2020 at 5:54 PM Arnd Bergmann <arnd@xxxxxxxx> > > > wrote: > > > > > > On Wed, Feb 12, 2020 at 9:50 AM Russell King - ARM Linux admin > > > > > > <linux@xxxxxxxxxxxxxxx> wrote: > > > > > > > > > > The CIP-supported RZ/G1 SoCs can have up to 4 GiB, typically split > (even > > > > > for 1 GiB or 2 GiB configurations) in two parts, one below and one > above > > > > > the 32-bit physical limit. > > > > Yep. One example is r8a7743-iwg20m.dtsi. > > This one has 2x512MB, with half above the 4GiB limit. This means it needs > LPAE to address high physical addresses (which is fine), but it does not need > highmem if one uses an appropriate CONFIG_VMSPLIT_* option. > > > > > Good to know. I think there are several other chips that have dual- > channel > > > > DDR3 and thus /can/ support this configuration, but this rarely happens. > > > > Are you aware of commercial products that use a 4GB configuration, > aside > > > from > > > > the reference board? > > > > iWave Systems make a range of SOM modules using the RZ/G1 SoCs. > > I believe there are options for some of these to use 4 GB, although 1 or 2 > GB is > > used in the boards we've upstreamed support for. > > > > There are also other SOM vendors (e.g. Emtrion) and end users of RZ/G1, > > but I'm not sure of the details. > > Both iWave and Emtrion only seem to list boards with 2GB or less on their > websites today (with up to 15 year availability). My guess is that they had > the same problem as everyone else in finding the right memory chips in > the required quantities and/or long-term availability. iWave lists "By default > 1GB DDR3 and 4GB eMMC only supported. Contact iWave for memory > expansion support." on some boards, but that doesn't mean they ever > shipped a 4GB configuration. I probably should have been clearer before - I actually have a couple of iWave RZ/G1M SOM modules with 4GB DDR on them. However I've never booted them nor do I know what the memory mapping is. Kind regards, Chris > > Arnd
