[Arm-netbook] 9nov11: progress on allwinner A10

[Gordan Bobic]

On 09/11/2011 20:44, Luke Kenneth Casson Leighton wrote:
> ok, just a quick thoughts / status update.
>
> we've had it confirmed that the CPU is external 2gb addressing but
> *internal* limited to 1gb (!)
>
> little factory is still going over the BOM, but want to put in 512mb
> DDR RAM ICs because they're cheaper.

That's a shame. IMO the biggest shortcomming of available devices is 
small RAM. I can just about live with 1GB, 2GB would be nice. Especially 
since the development version of OLPC is available with 3GB (Marvell).

> they were planning to make room for up to 4gb NAND flash *but*...
> something just occurred to me / my associates: thailand's under water.
>
> the implications of that are that the factories which used to make
> low-end IDE drives and pretty much every SATA drive under 80gb no
> longer exist... and probably won't ever be rebuilt.  everyone's moving
> to SSDs for low-end, and the prices for larger HDDs are rapidly
> escalating.
>
> now, for free software developers we don't give a rat's arse: there's
> always room to cut down to emdebian, or use cramfs, or... whatever:
> there's always creative ways to make a bit more room, but i've been
> connecting the dots a bit from various peoples' input, talked it over
> with my associates and we came up with an idea.

I'm not sure what the point is of having internal flash if you have a 
SD/uSD slot AND a SATA port. Dropping internal NAND alltogether seems 
like an obvious choice.

> alain (williams) asked a very pertinent question, he said, "ok yep
> count me in, but how do i make any money from this?" and it put me on
> the spot and i went, "um, well... how about you do servers but use
> these as low-power ones" and then i realised of course, he's a CentOS
> maintainer, hosts some packages, so he's going to try CentOS for ARM
> and then well if that works, he'll be the maintainer of the ARM port
> of CentOS servers.

I may have beaten him to it. I have a beta spin of RHEL6 port for ARM 
running right now with all relevant packages patched as required and 
built. :)

If anybody is interested in it, drop me a line and I'll notify you when 
it is downloadable (probably about a week, two at the most).

> then we put two and two together and went, "hang on, these are
> effectively blades, why not have a chassis like the ZT-Systems one,
> with a gigabit backbone, space for SATA drives, and up to 8
> EOMA-PCMCIA-compliant CPU cards, each with 1gb DDR3 RAM and these
> Cortex A8s?" it'll all be low-cost, you can get 40gb to 80gb SATA
> drives, turn it into a big software RAID or NAS box or a
> high-performance (but higher-than-average latency of course)
> load-balanced server aka cloud jobbie.

I like this idea - A LOT. I'd certainly be interested in buying some.

> at which point i went "oh shit - low-end SATA drives don't bloody
> *exist* any more!" :)  [look on ebuyer's site for SATA drives below
> £50 - there aren't any].

Well, on something this low power you'd want SSDs anyway.

> so _then_ i thought, hang on, NAND flash ICs in SSDs are like,
> dropping like a stone as they pick up the slack from the fact that
> low-end SATA and IDE drives don't exist, hmm, and the spec on the
> allwinner CPU says that it has 8 NAND chip-select lines... why not ask
> the little factory in shenzen if they can make room (on the other side
> of the PCMCIA card) for another 7 4gb NAND flash ICs?
>
> so if you wanted a "cheap" low-cost version, it'd be 512mb RAM with
> maybe a single 1gb NAND flash IC; the next version up would be 1gb RAM
> with a single 4gb NAND flash IC (again, single-sided so it's a cheaper
> build cost); the insane version would be effectively its own SSD with
> up to 32gb NAND flash, potentially 8x the speed of the 4gb version,
> and people could do their own wear-levelling (i hope!), i remember how
> everyone keeps bitching about how these bloody SSDs always get in the
> way with the stupid, stupid assumption that there's going to be a FAT
> or NTFS partition on it.

Hmm... Doing your own wear leveling? How quaint...

> bottom line: anyone grok the above, would want to sell these
> "promised" ARM-based servers we keep hearing about, but like, y'know,
> actual real ones, please do speak up, and i'll see how to arrange it.
> bear in mind that, thanks to the EOMA-PCMCIA specification, it will be
> possible to swap out the CPU cards with anything else that comes along
> in the future which also has 10/100 ethernet and SATA-II (possibly a
> Cortex A9 which would then have virtualisation - A8s *don't* have
> virtualisation), but no, you can't have 10/100/1000 or SATA-III this
> really _is_ at the "low-cost" and "low-power" end, going a bit on the
> odd side perhaps, pushing that "low-power equals a bit higher latency"
> thing a bit further along than is usually expected, but i believe the
> concept has merit.
>
> but... what's more important than what _i_ think has merit is what
> _you_ think has merit :)

I think the server idea is _great_, provided it has at least 1GB of RAM 
per board, a SATA port and at least 100Mb networking. Sign me up for 
some of those for sure. OTOH, I am not sure I see the point of having 
on-board raw NAND instead of a uSD slot. Yes, even the fastest SD cards 
are painfully slow when it comes to write IOPS, but arguably raw NAND 
won't be all that much better for any serious workload. In reality, I 
don't really see it getting used in a server setup except for a few KB 
for uboot settings. Everything else on a server will be on an SSD.

Gordan