From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28esmtp07.in.ibm.com (e28smtp07.in.ibm.com [59.145.155.7]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e28smtp07.in.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id DE18ADE0BB for ; Fri, 11 Jul 2008 21:10:34 +1000 (EST) Received: from d28relay02.in.ibm.com (d28relay02.in.ibm.com [9.184.220.59]) by e28esmtp07.in.ibm.com (8.13.1/8.13.1) with ESMTP id m6BB9S9O024739 for ; Fri, 11 Jul 2008 16:39:28 +0530 Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay02.in.ibm.com (8.13.8/8.13.8/NCO v9.0) with ESMTP id m6BB80cC745698 for ; Fri, 11 Jul 2008 16:38:00 +0530 Received: from d28av05.in.ibm.com (loopback [127.0.0.1]) by d28av05.in.ibm.com (8.13.1/8.13.3) with ESMTP id m6BB9S0Z006389 for ; Fri, 11 Jul 2008 16:39:28 +0530 From: Chandru To: Nathan Fontenot Subject: Re: [PATCH 1/4] kdump : add support for ibm, =?iso-8859-1?q?=09dynamic-reconfiguration-memory_for?= kexec/kdump Date: Fri, 11 Jul 2008 16:39:21 +0530 References: <200807080014.24910.chandru@in.ibm.com> <48768CE9.2080802@austin.ibm.com> In-Reply-To: <48768CE9.2080802@austin.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Message-Id: <200807111639.22032.chandru@in.ibm.com> Cc: linuxppc-dev@ozlabs.org, kexec@lists.infradead.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Friday 11 July 2008 03:57:53 Nathan Fontenot wrote: > Hello Chandru, > > > static int __init early_init_dt_scan_drconf_memory(unsigned long node) > > { > > - cell_t *dm, *ls; > > + cell_t *dm, *ls, *endp, *usm; > > unsigned long l, n, flags; > > u64 base, size, lmb_size; > > + char buf[32], t[8]; > > > > ls = (cell_t *)of_get_flat_dt_prop(node, "ibm,lmb-size", &l); > > if (ls == NULL || l < dt_root_size_cells * sizeof(cell_t)) > > @@ -917,7 +918,33 @@ static int __init early_init_dt_scan_drc > > if ((base + size) > 0x80000000ul) > > size = 0x80000000ul - base; > > } > > - lmb_add(base, size); > > + strcpy(buf, "linux,usable-memory"); > > + sprintf(t, "%d", (int)n); > > + strcat(buf, t); > > + usm = (cell_t *)of_get_flat_dt_prop(node, > > + (const char *)buf, &l); > > + if (usm != NULL) { > > + endp = usm + (l / sizeof(cell_t)); > > + while ((endp - usm) >= (dt_root_addr_cells + > > + dt_root_size_cells)) { > > + base = dt_mem_next_cell(dt_root_addr_cells, > > + &usm); > > + size = dt_mem_next_cell(dt_root_size_cells, > > + &usm); > > + if (size == 0) > > + continue; > > + if (iommu_is_off) { > > + if ((base + size) > 0x80000000ul) > > + size = 0x80000000ul - base; > > + } > > + lmb_add(base, size); > > + } > > + > > + /* Continue with next lmb entry */ > > + continue; > > + } else { > > + lmb_add(base, size); > > + } > > } > > I am still digging through the kexec tools but I don't think you want > the processing of the linux,usable-memory property inside of the > for (; n!= 0; --n) loop. This should be moved up so that it looks for > the linux,usable-memory property and parses it, then if it is not found > look for the ibm,dynamic-reconfiguration-memory property and parse it. > > There is no need to look for the linux-usable-memory property every time > a piece of the ibm,dynamic-reconfiguration-memory property is parsed. > > -Nathan Hello Nathan, Thanks for the review. kexec-tools adds a 'linux,usable-memory' property for each memory range listed in the device tree. If the regions are not crashkernel or rtas or tce regions, then it sets base and size to zero but still adds them as linux,usable-memory property. If we look at the code above, in a kdump kernel we don't add an lmb through lmb_add() if the regions are not one of the mentioned above. We check for (size == 0) and continue with next lmb if it is so. We still have the complete device tree which kexec-tools passes in as the buffer that we are scanning here and linux,usable-memory properties aid in making kdump kernel to see only those memory regions that it is suppose to use. I just worked on another version of this patch based on comments from Michael Neuling and Stephen Rothwell. I will post it shortly. Thanks, Chandru