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

From: Alexander Graf
Subject: Re: [Qemu-ppc] [PATCH] pseries: Correct RAM size check for SLOF
Date: Fri, 11 Nov 2011 11:51:12 +0100
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/20110221 SUSE/3.1.8 Thunderbird/3.1.8

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
@@ -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

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).


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