[POWERPC] pseries/phyp dump: Reserve a variable amount of space at boot

This changes the way we calculate how much space to reserve for the
pHyp dump.  Currently we reserve 256MB only.  With this change, the
code first checks to see if an amount has been specified on the boot
command line with the "phyp_dump_reserve_size" option, and if so, uses
that much.

Otherwise it computes 5% of total ram and rounds it down to a multiple
of 256MB, and uses the larger of that or 256MB.

This is for large systems with a lot of memory (10GB or more).  The
aim is to have more space available for the kernel on reboot on
machines with more resources.  Although the dump will be collected
pretty fast and the memory released really early on allowing the
machine to have the full memory available, this alleviates any issues
that can be caused by having way too little memory on very very large
systems during those few minutes.

Signed-off-by: Manish Ahuja <mahuja@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/include/asm-powerpc/phyp_dump.h b/include/asm-powerpc/phyp_dump.h
index 209a98913d9d..fa74c6c3e106 100644
--- a/include/asm-powerpc/phyp_dump.h
+++ b/include/asm-powerpc/phyp_dump.h
@@ -24,8 +24,10 @@ struct phyp_dump {
         /* Memory that is reserved during very early boot. */
         unsigned long init_reserve_start;
         unsigned long init_reserve_size;
-        /* Check status during boot if dump supported, active & present*/
+        /* cmd line options during boot */
+        unsigned long reserve_bootvar;
         unsigned long phyp_dump_at_boot;
+        /* Check status during boot if dump supported, active & present*/
         unsigned long phyp_dump_configured;
         unsigned long phyp_dump_is_active;
         /* store cpu & hpte size */