Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752888AbaGaWW7 (ORCPT ); Thu, 31 Jul 2014 18:22:59 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:52389 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750789AbaGaWW6 (ORCPT ); Thu, 31 Jul 2014 18:22:58 -0400 Date: Thu, 31 Jul 2014 15:22:55 -0700 From: Andrew Morton To: Vasant Hegde Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Linus Torvalds , Benjamin Herrenschmidt Subject: Re: [PATCH v2 1/2] printk: Add function to return log buffer address and size Message-Id: <20140731152255.37e675870dfdf77d9dbaff70@linux-foundation.org> In-Reply-To: <20140731153447.27134.44225.stgit@hegdevasant.in.ibm.com> References: <20140731153447.27134.44225.stgit@hegdevasant.in.ibm.com> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 31 Jul 2014 21:05:48 +0530 Vasant Hegde wrote: > Platforms like IBM Power Systems supports service processor > assisted dump. It provides interface to add memory region to > be captured when system is crashed. > > During initialization/running we can add kernel memory region > to be collected. > > Presently we don't have a way to get the log buffer base address > and size. This patch adds support to return log buffer address > and size. > > ... > > --- a/include/linux/printk.h > +++ b/include/linux/printk.h > @@ -10,6 +10,9 @@ > extern const char linux_banner[]; > extern const char linux_proc_banner[]; > > +extern void *get_log_buf_addr(void); > +extern u32 get_log_buf_len(void); > + > static inline int printk_get_level(const char *buffer) > { > if (buffer[0] == KERN_SOH_ASCII && buffer[1]) { > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c > index 13e839d..4049f7b 100644 > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -270,6 +270,18 @@ static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); > static char *log_buf = __log_buf; > static u32 log_buf_len = __LOG_BUF_LEN; > > +/* Return log buffer address */ > +void *get_log_buf_addr(void) > +{ > + return log_buf; > +} > + > +/* Return log buffer size */ > +u32 get_log_buf_len(void) > +{ > + return log_buf_len; > +} > + > /* human readable text of the record */ > static char *log_text(const struct printk_log *msg) > { Looks OK to me, although I think log_buf_addr_get() and log_buf_len_get() would be better names. The kernel uses some big-endian names and some little-endian-names and some middle-endian names. It's all rather a mess. These symbols are already big-endian (ie: decreasing significance): log_buf -> addr -> get log_buf -> len -> get The world wouldn't end if we simply made log_buf and log_buf_len global symbols. The pros and cons are all minor. It's probably better to make get_log_buf_addr() tell the truth and return a char *. Please include this in whatever tree carries "powerpc/powernv: Interface to register/unregister opal dump region". -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/