From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from moutng.kundenserver.de (moutng.kundenserver.de [212.227.126.187]) by ozlabs.org (Postfix) with ESMTP id ABE3DDDFE4 for ; Thu, 14 May 2009 02:01:44 +1000 (EST) From: Arnd Bergmann To: Benjamin Herrenschmidt Subject: [PATCH 1/3] powerpc/cell: make ptcal more reliable Date: Wed, 13 May 2009 17:50:46 +0200 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Message-Id: <0ML21M-1M4Gtp1PZb-0001oc@mrelayeu.kundenserver.de> Cc: Gerhard Stenzel , linuxppc-dev@ozlabs.org, Jeremy Kerr List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Gerhard Stenzel There have been a series of checkstops on QS21 related to ptcal being set up incorrectly. On systems that only have memory on a single node, ptcal fails when it gets a pointer to memory on the remote node. Moreover, agressive prefetching in memcpy and other functions may accidentally touch the first cache line of the page that we reserve for ptcal, which causes an ECC checkstop. We now allocate pages only from the specified node, moves the ptcal area into the middle of the allocated page to avoid potential prefetch problems and prints the address of the ptcal area to facilitate diagnostics. Signed-off-by: Gerhard Stenzel Signed-off-by: Arnd Bergmann --- arch/powerpc/platforms/cell/ras.c | 17 ++++++++++++++--- 1 files changed, 14 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/platforms/cell/ras.c b/arch/powerpc/platforms/cell/ras.c index 5f961c4..296b526 100644 --- a/arch/powerpc/platforms/cell/ras.c +++ b/arch/powerpc/platforms/cell/ras.c @@ -122,12 +122,23 @@ static int __init cbe_ptcal_enable_on_node(int nid, int order) area->nid = nid; area->order = order; - area->pages = alloc_pages_node(area->nid, GFP_KERNEL, area->order); + area->pages = alloc_pages_node(area->nid, GFP_KERNEL | GFP_THISNODE, + area->order); - if (!area->pages) + if (!area->pages) { + printk(KERN_WARNING "%s: no page on node %d\n", + __func__, area->nid); goto out_free_area; + } - addr = __pa(page_address(area->pages)); + /* + * We move the ptcal area to the middle of the allocated + * page, in order to avoid prefetches in memcpy and similar + * functions stepping on it. + */ + addr = __pa(page_address(area->pages)) + (PAGE_SIZE >> 1); + printk(KERN_DEBUG "%s: enabling PTCAL on node %d address=0x%016lx\n", + __func__, area->nid, addr); ret = -EIO; if (rtas_call(ptcal_start_tok, 3, 1, NULL, area->nid, -- 1.5.6.3