Re: [Babel-users] [Cerowrt-devel] Cross-compiling to armhf [was: beaglebone green wireless boards...]
> On 24 Jun, 2016, at 01:57, Juliusz Chroboczek > wrote: > >> the long slow EABI changeover that was obsoleted almost overnight by the >> armhf work the raspian folk did, and so on. > > I am pretty positive that armhf predates raspbian. Let's please give > credit where credit is due. Ironically, it was I who demonstrated to the Raspbian folks the benefits of an armhf build for the R-Pi 1, back in the early days of that platform. It seems like an awfully long time ago now. :-) I did it by building Gentoo in armhf mode - *on* my R-Pi 1 - and distributing the ready-built rootfs. To do this, I simply started from a softfp Gentoo build, and rebuilt it from the ground up using the Stage 1 bootstrap method. All the tools and support simply worked from that point on. At the time, ARMv7 distros were already typically built in armhf mode, but ARMv6 machines were usually expected to use softfp (or even softfloat) builds originally intended for ARMv5. Since the R-Pi was obviously going to be a “platform standard” and would always include an FPU, the effort of producing a proper ARMv6-hf build was justified. - Jonathan Morton ___ Babel-users mailing list Babel-users@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/babel-users
Re: [Babel-users] [Cerowrt-devel] Why we are discussing ARM [was: Cross-compiling to armhf]
> On 24 Jun, 2016, at 03:02, Juliusz Chroboczek > wrote: > > Raspberry Pi: doesn't run armhf userspace, no wifi, eth connected by USB; > Raspberry Pi v2/v3: requires binary blobs, wifi and eth connected over USB; Actually, the only substantial difference between the first R-Pi and the second is one ARM1176JZF-S core (ARMv6 with an FPU) versus four Cortex-A7s (ARMv7-A with FPU and SIMD). They can both run armhf userspace, as we were just discussing, and they can both have external wifi attached via USB. What the first version *can’t* do is run ARMv7 code - which isn’t very much of a difference, honestly. There is a big performance jump though. The third, current version gets four Cortex-A53s (which support AArch64 as well as 32-bit code) and includes a built-in wifi radio attached via SDIO. Otherwise, it’s identical to the second version. I haven’t got one of these yet. I’m told that all the official R-Pi distros remain 32-bit for compatibility with the older versions, but that’s not a concern if you’re rolling your own. They also *all* require a binary blob to bootstrap the chip. Apparently Broadcom’s SoC architecture puts the GPU - which occupies the lion’s share of the die area - in charge of boot, with the CPU subordinate. In fact the original R-Pi’s chip was designed as an independent embedded-class GPU, with its ARM core provided as a mere command translator! Needless to say, the GPU hardware goes woefully underutilised, but is retained in the newer versions to preserve compatibility. I agree however that none of the R-Pis make good routers at the performance levels we want. They just don’t have the right kind of I/O: we need direct or PCIe attachment of Ethernet and wifi MACs, not USB and SDIO. - Jonathan Morton ___ Babel-users mailing list Babel-users@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/babel-users
Re: [Babel-users] [Cerowrt-devel] Why we are discussing ARM [was: Cross-compiling to armhf]
> On 26 Jun, 2016, at 22:02, Baptiste Jonglez > wrote: > >> Do you know how the Ethernet is hooked to the SoC? I could be wrong, but >> I don't think Allwinner SoCs include GMII. > > I suggest you look at the schematics (here for LIME2): > > > https://github.com/OLIMEX/OLINUXINO/raw/master/HARDWARE/A20-OLinuXino-LIME2/A20-OLinuXino-Lime2_Rev_G.pdf > > Looking quickly, this looks like a SPI interface. I'm really not a > hardware expert though, so you'd better check yourself. It looks like GMII to me. That’s a good thing. SPI would be extremely unlikely - it just doesn’t have that sort of bandwidth, and I’ve never heard of it being used to attach Ethernet before. It appears that some of the pins used for GMII on the AllWinner are shared with one of the SPI interfaces (and a serial UART) - they can be used for one purpose or the other, but not both. This is quite common practice in the embedded world. - Jonathan Morton ___ Babel-users mailing list Babel-users@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/babel-users