On Mon, 26 Apr 2010 16:49:55 -0700 "H. Peter Anvin" <hpa@xxxxxxxxx> wrote: > > Sorry, sounds like we're talking about a few different things here: > > 1) devices which sit in e820 reserved space (whether at < 1M or > 1M) > > 2) devices which sit in e820 ram or other space below 1M > > 3) how to hand out space from the 0-1M region > > > > Bjorn's patch fixes (3) so that regular PCI devices don't get space > > there, which makes sense. > > > > Some devices may be in the special region, but were pointed there by > > the BIOS. Generally this should be ok, so drivers requesting this > > space should be allowed to get at it, but we should avoid putting > > anything else there. > > > > And below it sounds like you're talking about (1). If so, then yes I > > guess we need a solution there, which will allow drivers to bind to > > these "reserved" devices, even though the BIOS has marked them as off > > limits, at least as far as e820 goes. > > > > So perhaps both (1) and (2) could be put into a new, special IO > > resource space, or could use a new flag, since "busy" doesn't really > > reflect what's going on there very well, as Bjorn pointed out. > > > > Jesse > > Properly done, these aren't separate cases at all. > > The E820 interface as specified doesn't reserve the address space below 1 > MB, because it is legacy space -- which is another way of saying "everyone > already knows to reserve it." The Right Thing[TM] to do is simply to > modify the data output by E820 to reserve all non-memory space below 1 MB; > this can (and should) be done in platform-specific initialization code to > allow overrides. > > Once that is done, both your (2) and (3) cases are nothing but special > subcases of (1). That's what I would like to see as the right solution, > but it is clearly too late to do that in .34. > > Bjorn's solution is very attractive for .34 since it is so simple, but > it's not a complete solution. Glad we agree. As I said (and echoing Bjorn), I think it would be best to reserve this space in a way that doesn't just use IORESOURCE_BUSY. We want and need to do allocations from the special region, so we should mark it as such. -- Jesse Barnes, Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
