Messages in this thread Patch in this message | | | Date | Mon, 26 Apr 2010 14:07:51 -0700 | From | Yinghai <> | Subject | Re: [PATCH] x86/PCI: never allocate PCI MMIO resources below BIOS_END |
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On 04/26/2010 01:37 PM, Jesse Barnes wrote: > On Mon, 26 Apr 2010 14:27:56 -0600 >> I think it also leads to at least one problem: Guenter's machine has no >> VGA but has a PCI device that lives at 0xa0000. The driver for that >> device won't be able to request that region if the arch code has marked >> it busy. > > Ah good point, so we'll want another approach at any rate. Yinghai?
With current linus's tree, there is some difference between mmio > 1M and MMIO < 1M.
Actually it does not care about E820_RESERVED for > 1M range, because it doesn't have _BUSY.
For < 1M range, a. MMIO is not with E820_RESERVED, the device driver will work. b. MMIO is with E820_RESERVED, the device driver can not reserve it's mmio later. because that MMIO could have parent resource with "reserved" name and _BUSY flag
My patch -v3 will break a. but my patch -v4 patch will make it work.
but looks -v4 is too tricky.
maybe we just need remove change like following.
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index 7bca3c6..9849824 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -1094,7 +1094,7 @@ void __init e820_reserve_resources(void) * pci device BAR resource and insert them later in * pcibios_resource_survey() */ - if (e820.map[i].type != E820_RESERVED || res->start < (1ULL<<20)) { + if (e820.map[i].type != E820_RESERVED) { res->flags |= IORESOURCE_BUSY; insert_resource(&iomem_resource, res); } May need Linus to ack it.
Those strange devices could be some kind of virtual debug devices. and they like to use those low mmio range.
YH
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