110 lines
4.5 KiB
Diff
110 lines
4.5 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
|
|
From: Daniel Axtens <dja@axtens.net>
|
|
Date: Mon, 6 Feb 2023 10:03:20 -0500
|
|
Subject: [PATCH] ieee1275: request memory with ibm,
|
|
client-architecture-support
|
|
|
|
On PowerVM, the first time we boot a Linux partition, we may only get
|
|
256MB of real memory area, even if the partition has more memory.
|
|
|
|
This isn't enough to reliably verify a kernel. Fortunately, the Power
|
|
Architecture Platform Reference (PAPR) defines a method we can call to ask
|
|
for more memory: the broad and powerful ibm,client-architecture-support
|
|
(CAS) method.
|
|
|
|
CAS can do an enormous amount of things on a PAPR platform: as well as
|
|
asking for memory, you can set the supported processor level, the interrupt
|
|
controller, hash vs radix mmu, and so on.
|
|
|
|
If:
|
|
|
|
- we are running under what we think is PowerVM (compatible property of /
|
|
begins with "IBM"), and
|
|
|
|
- the full amount of RMA is less than 512MB (as determined by the reg
|
|
property of /memory)
|
|
|
|
then call CAS as follows: (refer to the Linux on Power Architecture
|
|
Reference, LoPAR, which is public, at B.5.2.3):
|
|
|
|
- Use the "any" PVR value and supply 2 option vectors.
|
|
|
|
- Set option vector 1 (PowerPC Server Processor Architecture Level)
|
|
to "ignore".
|
|
|
|
- Set option vector 2 with default or Linux-like options, including a
|
|
min-rma-size of 512MB.
|
|
|
|
- Set option vector 3 to request Floating Point, VMX and Decimal Floating
|
|
point, but don't abort the boot if we can't get them.
|
|
|
|
- Set option vector 4 to request a minimum VP percentage to 1%, which is
|
|
what Linux requests, and is below the default of 10%. Without this,
|
|
some systems with very large or very small configurations fail to boot.
|
|
|
|
This will cause a CAS reboot and the partition will restart with 512MB
|
|
of RMA. Importantly, grub will notice the 512MB and not call CAS again.
|
|
|
|
Notes about the choices of parameters:
|
|
|
|
- A partition can be configured with only 256MB of memory, which would
|
|
mean this request couldn't be satisfied, but PFW refuses to load with
|
|
only 256MB of memory, so it's a bit moot. SLOF will run fine with 256MB,
|
|
but we will never call CAS under qemu/SLOF because /compatible won't
|
|
begin with "IBM".)
|
|
|
|
- unspecified CAS vectors take on default values. Some of these values
|
|
might restrict the ability of certain hardware configurations to boot.
|
|
This is why we need to specify the VP percentage in vector 4, which is
|
|
in turn why we need to specify vector 3.
|
|
|
|
Finally, we should have enough memory to verify a kernel, and we will
|
|
reach Linux. One of the first things Linux does while still running under
|
|
OpenFirmware is to call CAS with a much fuller set of options (including
|
|
asking for 512MB of memory). Linux includes a much more restrictive set of
|
|
PVR values and processor support levels, and this CAS invocation will likely
|
|
induce another reboot. On this reboot grub will again notice the higher RMA,
|
|
and not call CAS. We will get to Linux again, Linux will call CAS again, but
|
|
because the values are now set for Linux this will not induce another CAS
|
|
reboot and we will finally boot all the way to userspace.
|
|
|
|
On all subsequent boots, everything will be configured with 512MB of RMA,
|
|
so there will be no further CAS reboots from grub. (phyp is super sticky
|
|
with the RMA size - it persists even on cold boots. So if you've ever booted
|
|
Linux in a partition, you'll probably never have grub call CAS. It'll only
|
|
ever fire the first time a partition loads grub, or if you deliberately lower
|
|
the amount of memory your partition has below 512MB.)
|
|
|
|
Signed-off-by: Daniel Axtens <dja@axtens.net>
|
|
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
|
|
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
|
|
(cherry picked from commit d5571590b7de61887efac1c298901455697ba307)
|
|
---
|
|
grub-core/kern/ieee1275/init.c | 13 +++++++++++++
|
|
1 file changed, 13 insertions(+)
|
|
|
|
diff --git a/grub-core/kern/ieee1275/init.c b/grub-core/kern/ieee1275/init.c
|
|
index 8ce1a0f09ee..13e8a5b4bb8 100644
|
|
--- a/grub-core/kern/ieee1275/init.c
|
|
+++ b/grub-core/kern/ieee1275/init.c
|
|
@@ -850,6 +850,19 @@ grub_claim_heap (void)
|
|
}
|
|
#endif
|
|
|
|
+#if defined(__powerpc__)
|
|
+ if (grub_ieee1275_test_flag (GRUB_IEEE1275_FLAG_CAN_TRY_CAS_FOR_MORE_MEMORY))
|
|
+ {
|
|
+ grub_uint64_t rma_size;
|
|
+ grub_err_t err;
|
|
+
|
|
+ err = grub_ieee1275_total_mem (&rma_size);
|
|
+ /* if we have an error, don't call CAS, just hope for the best */
|
|
+ if (err == GRUB_ERR_NONE && rma_size < (512 * 1024 * 1024))
|
|
+ grub_ieee1275_ibm_cas ();
|
|
+ }
|
|
+#endif
|
|
+
|
|
grub_machine_mmap_iterate (heap_init, &total);
|
|
}
|
|
#endif
|