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Re: [Qemu-devel] [PATCH 1/4] s390: sclp base support
From: |
Christian Borntraeger |
Subject: |
Re: [Qemu-devel] [PATCH 1/4] s390: sclp base support |
Date: |
Wed, 26 Sep 2012 18:06:33 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux i686; rv:15.0) Gecko/20120827 Thunderbird/15.0 |
On 26/09/12 17:00, Alexander Graf wrote:
>> +/* Provide information about the configuration, CPUs and storage */
>> +static void read_SCP_info(SCCB *sccb)
>> +{
>> + ReadInfo *read_info = (ReadInfo *) sccb;
>> + int shift = 0;
>> +
>> + while ((ram_size >> (20 + shift)) > 65535) {
>> + shift++;
>> + }
>> + read_info->rnmax = cpu_to_be16(ram_size >> (20 + shift));
>> + read_info->rnsize = 1 << shift;
>
> Any reason we can't just always expose rnmax2 and rnsize2 instead? This way
> we're quite limited on the amount of RAM we can support, right?
Well, we have 65535 * 256 * 1MB == 16TB which is ok for the next 2 or 3 years I
guess.
There are actually some rules that decide about rnmax vs rnmax2 etc, and here
the non-2 are appropriate. This might change for systems > 16TB or systems with
memory hotplug,
but I would prefer to use those for now. We will add the full logic in case we
add memory
hotplug.
[...]
>> + if (be16_to_cpu(work_sccb.h.length) < 8 ||
>
> sizeof(SCCBHeader)
ok
>
>> + be16_to_cpu(work_sccb.h.length) > 4096) {
>
> SCCB_SIZE
ok
>> */
>> -int sclp_service_call(CPUS390XState *env, uint32_t sccb, uint64_t code)
>> +int sclp_service_call(uint32_t sccb, uint64_t code)
>
> Why not move the whole thing into sclp.c? The only thing remaining here are a
> few sanity checks that would just as well work in generic sclp handling code,
> right?
The idea was two-fold:
- to have one single place were we cross between target-s390x and hw (review
feedback from the first series, originally we had all everything in sclp.c)
- to have the checks that the CPU can do over there and the complex things that
look into the sccb in sclp.c
But we could certainly move that, your take
Christian