Intel Controllers [Rant]

[Mark Felder]

On Dec 10, 2013, at 12:13, Jim Thompson <jim at netgate.com> wrote:

> On Tue, Dec 10, 2013 at 11:47 AM, Mark Felder <feld at freebsd.org> wrote:
>> On Mon, Dec 9, 2013, at 18:20, Barney Cordoba wrote:
>>> Why is it that every time I get a new MB it has yet-another intel
>>> controller on it? How are you supposed to write good drivers that support
>>> 9000 different controllers? As much as I appreciate the progression of
>>> CPU technology, they
>>> would serve the community better by making up their damn minds and just
>>> build 1 or 2 controller for each
>>> target market.
>>> 
>> 
>> I'm pretty sure an entirely new driver doesn't need to be written for
>> each new controller. I assume like with most things (network cards, wifi
>> chips, etc) it's usually a matter of adding its identifier to the driver
>> code.
> 
> It goes beyond that.   In the simplest case, then yes, things are as you say.
> 
> But chips have bugs, which require work-arounds, or other slightly
> strange stuff.
> 
> Case(s) in-point:
> 
> The 82575 assigns queues using vectors via a bitmask
> The Intel 82576 chip uses a table that essentially consists of 2
> columns with 8 rows.  The ordering is column-major (like Fortran
> arrays).
> On 82580 and newer adapters the scheme is similar to 82576, however
> instead of ordering column-major, the ordering is row-major (like C or
> Pascal).
> 
> These chips are all supported via the igb driver.
> 
> Some parts supported by the igb driver use MSI-X interrupts, others don't.
> 
> On i350, i354, i210, and i211, loopback VLAN packets have the tag byte-swapped.
> 
> The list of issues is by no means limited to the above.
> 
> Jim

That sounds tedious. Thanks to those of you that tirelessly hack away at these quirks.

When I first replied to this post I thought I was reading another list and the discussion was about disk controllers which don't seem to be so troublesome


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