* Yinghai Lu <yinghai@xxxxxxxxxx> wrote: > Ingo Molnar wrote: > > * Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > >> On Thu, 16 Apr 2009, Jesse Barnes wrote: > >>> Any comments on this one, Linus? Should I include your ack? > >> I'm not ready to ack it, no. I don't think the suggested patch is very > >> clean or necessarily sensible as-is. It seems very ad-hoc. > >> > >> I was literally thinking of something like > >> "round up from the last RAM by X" > >> "round up from the last reserved region by Y" > >> "pick the bigger of the two" > >> > >> with helper functions for the two cases and comments along the > >> lines of why we do it. Something that was a bit more obvious about > >> what it's doing and why. > > > > That's sensible - but i'd also like to inject hpa's add-on idea: if > > we do that then we should do it _explicitly_ and _visibly_, by > > injecting an artificial e820 reservation range to all expected > > "vulnerable" holes we cannot fully trust. > > > > We'd do that after all the fixed resources are allocated, but before > > dynamic PCI allocations. > > > > That prevents the PCI layer from dynamically allocating anything > > into that protective zone, and documents it as well (and makes it > > visible in boot logs, etc.) - instead of just a silent rule > > somewhere that no-one will really see if it breaks. > > that need to do done much earlier, and much simple, just need to > make that range to be reserved in e820. and later e820_setup_gap > even don't need to be aligned again. Well, an alignment _check_ could still be added with a WARN_ONCE(), to make sure these assumptions hold true in future as well. This kind of stuff is generally not testable and wont break on many systems - but it can easily cripple a random 0.5% of systems, creating a lot of unhappy users. So pretty much the only solution is to be careful, robust and redundant all along. Ingo -- 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
