pandoraPremium
join:2001-06-01
Outland
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| Can someone help me understand Linux and routers?? I have had various versions of Linux routers for a long time. My favorite version has been the Teddy Bear USB variant of Tomato.
I respect Open-WRT, DD-WRT, Tomato and the other versions of Linux as appealing to different types of people with diverse needs / wants.
My question is about Linux on some routers but not others. For example, the Linksys 4200. It comes in a V1 and V2 (aka Pro I think). Tomato is available on the V1, but not the V2. I understand the V2 uses different hardware, and has a different CPU. I'm not understanding why cross compilation works for one CPU type and not another.
Could someone who understands such things please explain to me why the CPU matters so much? I'm just not getting why one CPU / platform is easy but another is impossible.
Thanks
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"People demand freedom of speech as a compensation for the freedom of thought which they seldom use." |
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 shdesignsPowered By Infinite Improbabilty DrivePremium
join:2000-12-01
Stone Mountain, GA | Are you sure it is the CPU that is the limitation?
Many routers are excluded because the flash or RAM is too small in some versions. |
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| reply to pandora
shdesigns is correct in some sense since Linux is nothing but a Kernel and that's it. Unlike FreeBSD which is a full blown OS. You could compare FreeBSD to let's say Redhat or Slackware or as you said DD-WRT or Potato (refering to tomato lol )
So as for the CPU, each CPU may use a different binary set. CPUs like any other electronic gear other than analog speak 1s and 0s... Each CPU has its own MicroCode or Assembly language which it understands.
In order for one Kernel to run on a CPU it needs to rewritten/translated... but that's not just it. Each CPU has its own perks handling memory (which includes disks) and IO. In other words all have to be tested. Also, it's not just the CPU, but the BIOS as well as other chipsets that are involved.
A manufacturer looks at cost cutting vs. performance... So you'd see more low end chips placed into the routers that have higher performance... lol Electronically, speaking the advancement of technology on a month to month is pretty large for small chipsets so the newer the chipset the faster, i.e. the cheaper it is to build as the size of the chip is reduced. With the reduction a Manufacturer would like to keep the size the same or smaller to cut costs... |
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pandoraPremium
join:2001-06-01
Outland
kudos:1 Reviews:
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·Comcast
| reply to shdesigns
said by shdesigns:Are you sure it is the CPU that is the limitation?
Many routers are excluded because the flash or RAM is too small in some versions.
I think the E4200 V2 has 128 MB of flash and 128 MB of RAM. My current router has either 8MB or 16 MB of flash and either 32MB or 64MB of RAM.
I doubt it's RAM or Flash. 
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"People demand freedom of speech as a compensation for the freedom of thought which they seldom use." |
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pandoraPremium
join:2001-06-01
Outland
kudos:1 Reviews:
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| reply to Da Geek Kid
said by Da Geek Kid:In order for one Kernel to run on a CPU it needs to rewritten/translated... but that's not just it. Each CPU has its own perks handling memory (which includes disks) and IO. In other words all have to be tested. Also, it's not just the CPU, but the BIOS as well as other chipsets that are involved.
I appreciate your help. But Tomato and other distributions of Linux for routers are firmware. I think that makes them the BIOS as well.
I'm assuming you are saying cross system compilation isn't supported for a particular chipset or CPU perhaps?
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"People demand freedom of speech as a compensation for the freedom of thought which they seldom use." |
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Reviews:
·link2voip
 ·TekSavvy DSL
| reply to pandora
The CPU is not just a CPU, it's a System on Chip (SOC). Thus, the wireless controller and some other stuff is all integrated together there.
These SOCs require drivers, and if the manufacturer has not provided a Linux driver, or sufficient information for independent developers to be able to develop their own or free drivers, then Linux can't make use of them.
Tomato and all of its variants that I am aware of work with Broadcom SOCs only, because these are the drivers that are included in the Tomato Linux distro. Other distros such as dd-wrt have included support for other non-Broadcom hardware. In the case of the E4200v2, the SOC is a Marvell F6101AW, and it appears that no Linux distro supports it. Probably this is due to Marvell's decisions more than anybody else's.
I strongly encourage consumers, resellers, consultants, and Family Tech Support(TM) people everywhere to promote hardware that is properly supported by quality free software products like Tomato, OpenWRT, etc. My family, friends and customers may not know about SOCs and drivers, but they sure appreciate having a router that just works the way it should, and people who know me are sure to ask for my recommendation before they buy, and you can be sure that I recommend something that is known to run my favourite free firmware.
ref: »en.wikipedia.org/wiki/Linksys_routers#E4200
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pandoraPremium
join:2001-06-01
Outland
kudos:1 Reviews:
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·Comcast
| Thanks, that's the explanation I needed. It helped me understand why there isn't a distro for some routers. I wonder why Marvell wouldn't want Linux support for all it's devices. Though that isn't as big a concern.
Thanks again.
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"People demand freedom of speech as a compensation for the freedom of thought which they seldom use." |
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 mozerdLight Will Pierce The DarknessPremium,MVM
join:2004-04-23
Nepean, ON | Because they have some proprietary code that they do not want to expose at this time. Qualcomm does this all the time and with good reason ... its called a competitive edge. |
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pandoraPremium
join:2001-06-01
Outland
kudos:1 Reviews:
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| said by mozerd:Because they have some proprietary code that they do not want to expose at this time. Qualcomm does this all the time and with good reason ... its called a competitive edge.
I guess the perspective of a corporation is different than my personal perspective. However without ability to run Linux, I won't consider a router. My favorite variant is Tomato, but DD-WRT or Open-WRT would be acceptable also.
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"People demand freedom of speech as a compensation for the freedom of thought which they seldom use." |
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Reviews:
·link2voip
·TekSavvy DSL
| reply to mozerd
said by mozerd:Because they have some proprietary code that they do not want to expose at this time. Qualcomm does this all the time and with good reason ... its called a competitive edge.
While probably true, that's not the whole story. It's possible for a company like Marvell to release binary-only Linux drivers that will work with Linux without revealing any of their secrets. The problem here is that it puts an extra burden on them to employ a Linux driver team, and many companies can't be bothered. This underlines again the importance of putting your support behind companies that cooperate with your preferred firmware OS.
There is talk on linksysinfo.org recently that ASUS has published GPL code for some of their late model firmwares, with proper acknowledgement and credit to Tomato developers for the use of their code in ASUS's factory firmware. It's great to see a company embrace the free software philosophy and at least tacitly acknowledge that it can benefit both producer and consumer.
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