Re: [PATCH] Intel IXP4xx network drivers v.3 - QMGR

[Krzysztof Halasa <khc@pm.waw.pl>]

Lennert Buytenhek <buytenh@wantstofly.org> writes:

> See for example arch/arm/mach-ep93xx/core.c, handling of the A/B/F
> port GPIO interrupts.
>
> In a nutshell, it goes like this.

Thanks, I will investigate.

>> There may be up to 6 Ethernet ports (not sure about hardware
>> status, not yet supported even by Intel) - 7 queues * 128 entries
>> each = ~ 3.5 KB. Add 2 long queues (RX) for HSS and something
>> for TX, and then crypto, and maybe other things.
>
> You're unlikely to be using all of those at the same time, though.

That's the point.

> And what do you do if the user does compile all of these features into
> his kernel and then tries to use them all at the same time?  Return
> -ENOMEM?

If he is able to do so, yes - there is nothing we can do. But
I suspect a single machine would not have all possible hardware.
The problem is, we don't know what would it have, so it must be
dynamic.

> Shouldn't we make sure that at least the features that are compiled in
> can be used at the same time?

We can't - hardware capabilities limit that. A general purpose
distribution would probably want to compile in everything (perhaps
as modules).

>  If you want that guarantee, then you
> might as well determine the SRAM map at compile time.

That would be most limiting with IMHO no visible advantage.
-- 
Krzysztof Halasa
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