Re: [PATCH] UV2 - Bug fix for GRU global addresses

Andrew Morton
2011-09-08T23:51:43Z

(cc x86 maintainers)

On Thu, 8 Sep 2011 13:24:13 -0500
Jack Steiner <steiner@sgi.com> wrote:

> This patch is a workaround for a UV2 hub bug that affects the format
> of system global addresses.
>
> The GRU API for UV2 was inadvertently broken by a hardware change. The
> format of the physical address used for TLB dropins and for addresses used
> with instructions running in unmapped mode has changed. This change was not
> documented and became apparent only when diags failed running on system simulators.
>
> For UV1, TLB and GRU instruction physical addresses are identical to socket
> physical addresses (although high NASID bits must be OR'ed into the
> address).
>
> For UV2, socket physical addresses need to be converted. The NODE portion of
> the physical address needs to be shifted so that the low bit is in bit 39 or
> bit 40, depending on an MMR value.
>
> It is not yet clear if this bug will be fixed in a silicon respin. If it
> is fixed, the hub revision will be incremented & the workaround disabled.

It's unclear to me whether this patch should be merged into 3.1 and/or
into 3.0.x and earlier?