Hello!
> This turns out to be moderately hard since you have to use lspci to find
> the capability location, then look up the capability offset in the PCI
> spec, do the arithmetic and so on.
>
> One way we could make this easier is to allow symbolic names to
> refer to offsets from the starts of capabilities.
[...]
> First things first, though,
> is this an interesting feature to add?
An ability to address capabilities would be very welcome. On the other
hand, I think that it should not be limited to capabilities hard-wired
in setpci. Here is a sketch of a possible syntax:
<reg> = <base>[+<number>][.(B|W|L)] <-- can specify an offset
<base> = <number> <-- absolute position
| <named-register> <-- can be a part of a capability, too
| CAP_<name> <-- named capability
| ECAP_<name> <-- named PCIe capability
| CAP<number> <-- capability specified by its number
| ECAP<number> <-- the same for PCIe
(Offset addressing is not limited to capabilities intentionally, so that
it is for example possible to access a part of a named register. Also,
I have lifted the restriction that the explicit width must match the known
width of a named register.)
Does it make sense?
Have a nice fortnight
--
Martin `MJ' Mares <mj@xxxxxx> http://mj.ucw.cz/
Faculty of Math and Physics, Charles University, Prague, Czech Rep., Earth
return(ENOTOBACCO); /* Read on an empty pipe */
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