Messages in this thread | | | Date | Tue, 05 May 2009 12:28:53 +0900 | From | Tejun Heo <> | Subject | Re: [PATCHSET] block,scsi,libata: implement alt_size |
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Hello,
Dan Williams wrote: > On Mon, May 4, 2009 at 1:02 AM, Tejun Heo <tj@kernel.org> wrote: >>> Couldn't the "fix" also just be a note to users to disable ignore_hpa >>> if they notice that there raid arrays are not assembling correctly? >> I don't know. If it doesn't work automatically, the solution really >> isn't worth much. People generally don't (shouldn't need to) have any >> idea what HPA is. It basically boils down to "Linux doesn't support >> RAID". :-) >> >> Maybe we should just put this issue to the rest and strongly advise >> people against BIOS raids. > > That's a bit too far :-). The real issue is that Linux is ignoring a > property of the platform. To me ignoring HPA is like ignoring an e820 > reserved memory region. You might be able to get away with it > sometimes, but other times it breaks.
Well, somewhat but not quite. The difference is with backward compatibility and the fact that HPA has been used for many different creative ;-) purposes including working around BIOS limitations.
> However, in the end I think having 'alt_size' available is a useful > mechanism for discovering and handling the ignore_hpa=1 case. The > policy about when to trust it can be left to userspace.
Pushing this in the kernel without updating dm-raid is kind of pointless. Who should I be poking to get the userland part moving?
Thanks.
-- tejun
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