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Re: HVM disc corruption (was Re: Xen won't start its device backend?)

reinoud%NetBSD.org@localhost (Reinoud Zandijk) writes:

>wd0 reports it supports LBA48 still but i don't see a line claiming its using.
>It only reports PIO mode 4, DMA mode 2.

LBA48 changes how commands are written (some registers are written twice).
It has nothing to do with PIO or DMA.

>to xenkernel41 too. It feels more responsive but it still has the same mapping
>issue, so far no luck. What strikes me is that it is near bit 28, a kind of
>odd number unless the top 4 bits mean something else to code somewhere in the
>whole chain.

simple LBA is LBA28 because the old C/H/S registers are now used to
store 28 bits of a block number. LBA48 extends this to 48 bits.

The qemu code in xentools41 and 42 looks correct. Maybe there is an
issue with passing the I/O writes to Dom0 and qemu.

                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."

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