PCIe config and MMCONF

[Carl-Daniel Hailfinger]

MMCONF and PCIe BAR is a concept which has many different names in our
tree. It's almost impossible to find all code concerning MMCONFIG when
there are some hardcoded values and three different names for it.

MMCONF_BASE_ADDRESS, EXT_CONF_BASE_ADDRESS and DEFAULT_PCIEXBAR have the
same purpose. There are various places in the tree where that stuff is
hardcoded as 0xe0000000 or 0xf0000000 or 0xf4000000. Try grepping for
them. Bring antacid for your stomach.

Of course, that leads to bugs which are difficult to track down.

We need exactly one variable for the base address and another one for
the size of that area.

Ideas about the name?

Regards,
Carl-Daniel

[Peter Stuge]

Carl-Daniel Hailfinger wrote:
> MMCONF_BASE_ADDRESS, EXT_CONF_BASE_ADDRESS and DEFAULT_PCIEXBAR
> have the same purpose.
> We need exactly one variable for the base address and another one
> for the size of that area.

Yes.
> Ideas about the name?

Counter-question. Does this apply to anything but PCI Express? HT?
If it really is only PCI Express, then I like DEFAULT_PCIE_BAR or
maybe DEFAULT_PCIE_BAR_BASE and _SIZE. If not only PCI Express then
DEFAULT_EXT_BAR_BASE and _SIZE seems better.

//Peter

[Carl-Daniel Hailfinger]

On 14.05.2009 04:05, Peter Stuge wrote:
> Carl-Daniel Hailfinger wrote:
> > MMCONF_BASE_ADDRESS, EXT_CONF_BASE_ADDRESS and DEFAULT_PCIEXBAR
> > have the same purpose.
> > We need exactly one variable for the base address and another one
> > for the size of that area.
>
> Yes.
> > Ideas about the name?
>
> Counter-question. Does this apply to anything but PCI Express? HT?
> If it really is only PCI Express, then I like DEFAULT_PCIE_BAR or
> maybe DEFAULT_PCIE_BAR_BASE and _SIZE. If not only PCI Express then
> DEFAULT_EXT_BAR_BASE and _SIZE seems better.

AFAIK it applies to every PCI addressable device behind the bridge with
the MMCONFIG feature. On Fam10, this means all devices visible in PCI
config space, regardless of which bus they are on.

I do like your DEFAULT_EXT_BAR_{BASE,SIZE} suggestion. May I suggest a
small change to include PCI somewhere in the name? The meaning of the
variable should be at least somewhat obvious.

Regards,
Carl-Daniel

[Peter Stuge]

Carl-Daniel Hailfinger wrote:
> > Does this apply to anything but PCI Express? HT?
>
> AFAIK it applies to every PCI addressable device behind the bridge
> with the MMCONFIG feature.
> I do like your DEFAULT_EXT_BAR_{BASE,SIZE} suggestion. May I
> suggest a small change to include PCI somewhere in the name? The
> meaning of the variable should be at least somewhat obvious.

Either it is specific for PCI Express or it isn't. If not, PCIE
shouldn't be in the name.

If MMCONFIG is the term that applies, then better use that instead:

MMCONFIG_BAR_BASE and _SIZE

//Peter

[Tom Sylla]

On Wed, May 13, 2009 at 10:26 PM, Peter Stuge  wrote:
> If MMCONFIG is the term that applies, then better use that instead:
>
> MMCONFIG_BAR_BASE and _SIZE

One note, "BAR" might be a little bit confusing. "BAR" has a pretty
strong tie to an actual register in a PCI config header. I think the
variables you are describing are really just "the address and size
where MMCONFIG is located", not necessarily an actual register.

MMCONFIG_BASE and MMCONFIG_SIZE

seem pretty clear and simple

[Peter Stuge]

Tom Sylla wrote:
> > MMCONFIG_BAR_BASE and _SIZE
>
> One note, "BAR" might be a little bit confusing. "BAR" has a pretty
> strong tie to an actual register in a PCI config header.

Yes.
> I think the variables you are describing are really just "the
> address and size where MMCONFIG is located", not necessarily an
> actual register.

Aha!
> MMCONFIG_BASE and MMCONFIG_SIZE
>
> seem pretty clear and simple

Makes perfect sense. I want that.

//Peter

[Carl-Daniel Hailfinger]

On 14.05.2009 16:03, Peter Stuge wrote:
> Tom Sylla wrote:
> > MMCONFIG_BASE and MMCONFIG_SIZE
> >
> > seem pretty clear and simple
>
> Makes perfect sense. I want that.

Fully agreed.

Tom, thanks for coming up with that name.

Regards,
Carl-Daniel