Messages in this thread | | | Date | Fri, 29 Aug 2008 00:52:43 -0700 | From | "Yinghai Lu" <> | Subject | Re: [PATCH] x86: split e820 reserved entries record to late v4 |
| |
On Fri, Aug 29, 2008 at 12:28 AM, Ingo Molnar <mingo@elte.hu> wrote: > > * Yinghai Lu <yhlu.kernel@gmail.com> wrote: > >> On Thu, Aug 28, 2008 at 11:58 PM, Ingo Molnar <mingo@elte.hu> wrote: >> > >> > * Yinghai Lu <yhlu.kernel@gmail.com> wrote: >> > >> >> > BIOS-e820: 0000000077ff0000 - 0000000078000000 (reserved) >> >> > BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved) >> >> > BIOS-e820: 00000000fec00000 - 0000000100000000 (reserved) >> >> > >> >> > which overlaps with the chipset PCI BAR (hpet) resource: >> >> > >> >> > pci 0000:00:14.0: BAR has HPET at fed00000-fed003ff >> >> > >> >> > so due to this 1K conflict we take the full e820-reserved entry out and >> >> > give the range 0xfec00000-0x100000000 as 'free'. >> >> >> >> you will get >> >> fec00000 - ffffffff reserved >> >> fed0000 - fed003ff hpet >> >> fed0000 - fed003ff 0000:00:14.0 >> > >> > ok - because it's fully contained insert_resource() will succeed? I >> > thought it would only succeed if the new resource was smaller than (a >> > subset of) the existing resource. In the other direction, when a newly >> > inserted resource is a superset of the existing resource, i thought we'd >> > fail. >> > >> > hypothetical scenario, what if we had neither a superset nor a subset >> > scenario, but a partial overlap, between: >> > >> >> > BIOS-e820: 00000000fec00000 - 0000000100000000 (reserved) >> > >> > and: >> > >> >> > pci 0000:00:14.0: BAR has HPET at feb0f000-fec01000 >> > >> > i.e. we have: >> > >> > [... PCI BAR ...] >> > [... e820 reservation ...] >> > >> > in that case the insert_resource() will fail due to the conflict. Can we >> > declare it in that case that the e820 reserved entry is mortally broken >> > and we just ignore it? >> >> yes, that will fail to insert ... >> >> expand to 0xfeb0f000 - 0xfffffff and try again.? >> >> may need to update insert_resource to return conflict resource ... > > yes, that sounds an excellent idea - i was thinking of something > muchmore complex like breaking up the reserved entry - but indeed just > creating a large enough superset should be perfect. I.e. extend both > start and end until we fit fully. [or reach some natural boundary such > as 0 or 4GB] > >> > At least we should emit a prominent warning if insert_resource() fails, >> > and add in an mdelay(2000) so that the user sees it. >> >> right > > btw., perhaps we should try this: first try a request_resource(). If > that fails it means we overlap with something - then we should already > printk a warning. (e820 reserved entries should never conflict with PCI > resources, should they?) > > then try an insert_resource(). If that too fails it means a partial > overlap - printk another warning. Try the extension (within reasonable > limits) and retry. > > Does that sound worthwile?
request_resource should always fail at that case, because we are using iomem_resource at first parent...
YH
| |