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Re: [Qemu-ppc] [PATCH] pseries: Correct RAM size check for SLOF

From: David Gibson
Subject: Re: [Qemu-ppc] [PATCH] pseries: Correct RAM size check for SLOF
Date: Mon, 14 Nov 2011 12:44:19 +1100
User-agent: Mutt/1.5.21 (2010-09-15)

On Fri, Nov 11, 2011 at 11:51:12AM +0100, Alexander Graf wrote:
> On 11/08/2011 11:12 AM, Thomas Huth wrote:
> >Am Tue,  8 Nov 2011 16:52:16 +1100
> >schrieb David Gibson<address@hidden>:
> >
> >>The SLOF firmware used on the pseries machine needs a reasonable amount of
> >>(guest) RAM in order to run, so we have a check in the machine init
> >>function to check that this is available.  However, SLOF runs in real mode
> >>(MMU off) which means it can only actually access the RMA (Real Mode Area),
> >>not all of RAM.  In many cases the RMA is the same as all RAM, but when
> >>running with Book3S HV KVM on PowerPC 970, the RMA must be especially
> >>allocated to be (host) physically contiguous.  In this case, the RMA size
> >>is determined by what the host admin allocated at boot time, and will
> >>usually be less than the whole guest RAM size.
> >>
> >>This patch corrects the test to see if SLOF has enough memory for this
> >>case.
> >[...]
> >>@@ -562,9 +562,9 @@ static void ppc_spapr_init(ram_addr_t ram_size,
> >>
> >>          spapr->entry_point = KERNEL_LOAD_ADDR;
> >>      } else {
> >>-        if (ram_size<  (MIN_RAM_SLOF<<  20)) {
> >>+        if (rma_size<  (MIN_RMA_SLOF<<  20)) {
> >>              fprintf(stderr, "qemu: pSeries SLOF firmware requires>= "
> >>-                    "%ldM guest RAM\n", MIN_RAM_SLOF);
> >>+                    "%ldM guest RAM\n", MIN_RMA_SLOF);
> >Maybe it's more helpful for the unexperienced users when we change the
> >term "guest RAM" to "real mode area (RMA) memory" here? What do you
> >think?
> Yes, please. That's basically what the patch is changing, so the
> printf should be changed as well :). If you find it too confusing,
> you can say "%ldM guest RAM (RMA)". Whoever uses KVM on a 970 will
> have to manually allocate RMA regions in the first place, so he will
> know what it means. Everyone else will read RAM (which should be
> correct for p7 KVM and TCG).

Duh, yeah, oversight.  New version coming.

David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!

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