Looking at what the kernel does, looks like we should
- Check for more errors
- Try to execute !FORCED read if the FORCED one is unknown
- Set the function code to a normal write
- Set control_mask[2] to 0x80 (no idea what that means)
The kernel seems to set the function code to 0x80. Looking at where that
comes from, turns out this is a "dump indicator" to produce more
meaningful dumps. Looking for other function codes used in the kernel, I
discovered 0x40, which is used for "single increment assign" to speed up
memory hotplug. I was not able to find out what "control_mask[2] = 0x80"
means.
I guess we can just set the funcion code to 0 ("normal write). Let's
document the other bits in case anybody ever wonders what they mean.
Also, let's just set the other bits in the mask to 0, not sure if they
will actually be used, but this is definetly not wrong.
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
Quickly tested under kvm (on top of z/VM) and under tcg.
lib/s390x/sclp.c | 26 ++++++++++++++++++++++++--
lib/s390x/sclp.h | 2 ++
2 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
index 1d4a010..8224553 100644
--- a/lib/s390x/sclp.c
+++ b/lib/s390x/sclp.c
@@ -30,14 +30,36 @@ static void mem_init(phys_addr_t mem_end)
phys_alloc_init(freemem_start, mem_end - freemem_start);
}
+static void sclp_read_scp_info(ReadInfo *ri, int length)
+{
+ unsigned int commands[] = { SCLP_CMDW_READ_SCP_INFO_FORCED,
+ SCLP_CMDW_READ_SCP_INFO };
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(commands); i++) {
+ ri->h.length = length;
+ ri->h.function_code = SCLP_FC_NORMAL_WRITE;
+ ri->h.control_mask[0] = 0;
+ ri->h.control_mask[1] = 0;
+ ri->h.control_mask[2] = 0x80;
+
+ if (sclp_service_call(commands[i], ri))
+ break;
+ if (ri->h.response_code == SCLP_RC_NORMAL_READ_COMPLETION)
+ return;
+ if (ri->h.response_code != SCLP_RC_INVALID_SCLP_COMMAND)
+ break;
+ }
+ report_abort("READ_SCP_INFO failed");
+}
+
void sclp_memory_setup(void)
{
ReadInfo *ri = (void *)_sccb;
uint64_t rnmax, rnsize;
int cc;
- ri->h.length = SCCB_SIZE;
- sclp_service_call(SCLP_CMDW_READ_SCP_INFO_FORCED, ri);
+ sclp_read_scp_info(ri, SCCB_SIZE);
/* calculate the storage increment size */
rnsize = ri->rnsize;
diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
index 21d482b..131813e 100644
--- a/lib/s390x/sclp.h
+++ b/lib/s390x/sclp.h
@@ -76,6 +76,8 @@
#define SCLP_EVENT_BUFFER_ACCEPTED 0x80
#define SCLP_FC_NORMAL_WRITE 0
+#define SCLP_FC_SINGLE_INCREMENT_ASSIGN 0x40
+#define SCLP_FC_DUMP_INDICATOR 0x80
typedef struct SCCBHeader {
uint16_t length;
--
2.17.2
