powerpc: Revert support for ibm,drc-info devtree property

Message ID f5baf8d9-ece2-d3b8-2793-7701a1184c2a@linux.vnet.ibm.com
State Accepted
Commit c7a3275e0f9e461bb8942132aa6914aae59e7103
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Series
  • powerpc: Revert support for ibm,drc-info devtree property
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Commit Message

Michael Bringmann Feb. 13, 2018, 8:02 p.m.
This reverts commit 02ef6dd8109b581343ebeb1c4c973513682535d6.

The earlier patch tried to enable support for a new property
"ibm,drc-info" on powerpc systems.

Unfortunately, some errors in the associated patch set break things
in some of the DLPAR operations.  In particular when attempting to
hot-add a new CPU or set of CPUs, the original patch failed to
properly calculate the available resources, and aborted the operation.
In addition, the original set missed several opportunities to compress
and reuse common code.

As the associated patch set was meant to provide an optimization of
storage and performance of a set of device-tree properties for future
systems with large amounts of resources, reverting just restores
the previous behavior for existing systems.  It seems unnecessary
to enable this feature and introduce the consequent problems in the
field that it will cause at this time, so please revert it for now
until testing of the corrections are finished properly.

Signed-off-by: Michael W. Bringmann <mwb@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/prom_init.c     | 1 +
 1 files changed, 1 insertions(+), 1 deletions(-)

Comments

Michael Ellerman Feb. 23, 2018, 5:39 a.m. | #1
On Tue, 2018-02-13 at 20:02:53 UTC, Michael Bringmann wrote:
> This reverts commit 02ef6dd8109b581343ebeb1c4c973513682535d6.
> 
> The earlier patch tried to enable support for a new property
> "ibm,drc-info" on powerpc systems.
> 
> Unfortunately, some errors in the associated patch set break things
> in some of the DLPAR operations.  In particular when attempting to
> hot-add a new CPU or set of CPUs, the original patch failed to
> properly calculate the available resources, and aborted the operation.
> In addition, the original set missed several opportunities to compress
> and reuse common code.
> 
> As the associated patch set was meant to provide an optimization of
> storage and performance of a set of device-tree properties for future
> systems with large amounts of resources, reverting just restores
> the previous behavior for existing systems.  It seems unnecessary
> to enable this feature and introduce the consequent problems in the
> field that it will cause at this time, so please revert it for now
> until testing of the corrections are finished properly.
> 
> Signed-off-by: Michael W. Bringmann <mwb@linux.vnet.ibm.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/c7a3275e0f9e461bb8942132aa6914

cheers

Patch

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index adf044d..d22c41c 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -874,7 +874,7 @@  struct ibm_arch_vec __cacheline_aligned ibm_architecture_vec = {
 		.mmu = 0,
 		.hash_ext = 0,
 		.radix_ext = 0,
-		.byte22 = OV5_FEAT(OV5_DRC_INFO),
+		.byte22 = 0,
 	},
 
 	/* option vector 6: IBM PAPR hints */