Yes, you can refer to AR10040-03-POK, Service-Call Logical Processor Architecture for S/390 and z/Architecture, Figure 2-6 Minimum storage increment and subincrement size. :)
Nick
From: Alexander Graf <ag...@suse.de>
To: Jens Freimann <jf...@de.ibm.com>
Cc: Jens Freimann <jf...@linux.vnet.ibm.com>, Cornelia Huck
<cornelia.h...@de.ibm.com>, qemu-devel <qemu-devel@nongnu.org>,
Heinz Graalfs <graa...@linux.vnet.ibm.com>, Jeng-fang
Wang/Poughkeepsie/IBM@IBMUS
Date: 06/12/2012 07:53 AM
Subject: Re: [PATCH 8/8] s390: Fix the storage increment size
calculation
On 06/06/2012 02:05 PM, Jens Freimann wrote:
> From: Nick Wang<jfw...@us.ibm.com>
>
> To comply with the SCLP architecture, the number of storage
> increments should be 512 or fewer. The increment size is a
> multiple of 1M and is a power of 2.
>
> Signed-off-by: Nick Wang<jfw...@us.ibm.com>
> Signed-off-by: Jens Freimann<jf...@linux.vnet.ibm.com>
Any references to documentation for this one? :)
Alex
> ---
> hw/s390-sclp.c | 2 +-
> hw/s390-virtio.c | 6 +++---
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/hw/s390-sclp.c b/hw/s390-sclp.c
> index 8f45773..3e91f93 100644
> --- a/hw/s390-sclp.c
> +++ b/hw/s390-sclp.c
> @@ -32,7 +32,7 @@ int sclp_read_info(CPUS390XState *env, struct sccb
*sccb)
> {
> int shift = 0;
>
> - while ((ram_size>> (20 + shift))> 65535) {
> + while ((ram_size>> (20 + shift))> 512) {
> shift++;
> }
> sccb->c.read_info.rnmax = cpu_to_be16(ram_size>> (20 + shift));
> diff --git a/hw/s390-virtio.c b/hw/s390-virtio.c
> index 0babf27..9578d15 100644
> --- a/hw/s390-virtio.c
> +++ b/hw/s390-virtio.c
> @@ -175,9 +175,9 @@ static void s390_init(ram_addr_t my_ram_size,
> int i;
> DeviceState *dev;
>
> - /* s390x ram size detection needs a 16bit multiplier + an increment.
So
> - guests> 64GB can be specified in 2MB steps etc. */
> - while ((my_ram_size>> (20 + shift))> 65535) {
> + /* The storage increment size is a multiple of 1M and is a power of
2.
> + * The number of storage increments must be 512 or fewer. */
> + while ((my_ram_size>> (20 + shift))> 512) {
> shift++;
> }
> my_ram_size = my_ram_size>> (20 + shift)<< (20 + shift);
<<inline: graycol.gif>>
