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Re: [Qemu-devel] [PATCH v3] spapr: Add "memop" hypercall

From: Alexander Graf
Subject: Re: [Qemu-devel] [PATCH v3] spapr: Add "memop" hypercall
Date: Tue, 19 Jun 2012 22:57:28 +0200

On 19.06.2012, at 08:21, Benjamin Herrenschmidt wrote:

> This adds a qemu-specific hypervisor call to the pseries machine
> which allows to do what amounts to memmove, memcpy and xor over
> regions of physical memory such as the framebuffer.
> This is the simplest way to get usable framebuffer speed from
> SLOF since the framebuffer isn't mapped in the VRMA and so would
> otherwise require an hcall per 8 bytes access.
> The performance is still not great but usable, and can be improved
> with a more complex implementation of the hcall itself if needed.
> This also adds some documentation for the qemu-specific hypercalls
> that we add to PAPR along with a new qemu,hypertas-functions property
> that mirrors ibm,hypertas-functions and provides some discoverability
> for the new calls.
> Note: I chose note to advertise H_RTAS to the guest via that mechanism.
> This is done on purpose, the guest uses the normal RTAS interfaces
> provided by qemu (including SLOF) which internally calls H_RTAS.
> We might in the future implement part (or even all) of RTAS inside the
> guest like IBM's firmware does and replace H_RTAS with some finer grained
> set of private hypercalls.
> Signed-off-by: Benjamin Herrenschmidt <address@hidden>

Thanks, applied to ppc-next.


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