From mboxrd@z Thu Jan 1 00:00:00 1970 From: panand@redhat.com (Pratyush Anand) Date: Wed, 23 Nov 2016 07:16:26 +0530 Subject: [PATCH 2/2] arm64: Pass RAM boundary and enable-dcache flag to purgatory In-Reply-To: <53ee2a62-7822-5457-e59f-e65e64a57019@infradead.org> References: <53ee2a62-7822-5457-e59f-e65e64a57019@infradead.org> Message-ID: <54cad725-90f0-8dfe-bee6-fe1d3e02175d@redhat.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Geoff, On Wednesday 23 November 2016 12:27 AM, Geoff Levand wrote: > Hi Pratyush, > > On 11/21/2016 08:32 PM, Pratyush Anand wrote: >> When "enable-dcache" is passed to the kexec() command line, kexec-tools >> passes this information to purgatory, which in turn enables cache during >> sha-256 verification. > > What's the point of this enable-dcache option? Why not just > always enable the cache if we can? As I have written in changelog of patch 1/2 "We are supporting only 4K and 64K page sizes. This code will not work if a hardware is not supporting at least one of these page sizes. Therefore, D-cache is disabled by default and enabled only when "enable-dcache" is passed to the kexec()." Although this is very unlikely that a hardware will support only 16K page sizes, however it is possible. Therefore, its better to keep it disabled by default. ~Pratyush From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-qk0-f180.google.com ([209.85.220.180]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1c9MeC-0001jS-Pl for kexec@lists.infradead.org; Wed, 23 Nov 2016 01:46:53 +0000 Received: by mail-qk0-f180.google.com with SMTP id x190so49853358qkb.0 for ; Tue, 22 Nov 2016 17:46:32 -0800 (PST) Subject: Re: [PATCH 2/2] arm64: Pass RAM boundary and enable-dcache flag to purgatory References: <53ee2a62-7822-5457-e59f-e65e64a57019@infradead.org> From: Pratyush Anand Message-ID: <54cad725-90f0-8dfe-bee6-fe1d3e02175d@redhat.com> Date: Wed, 23 Nov 2016 07:16:26 +0530 MIME-Version: 1.0 In-Reply-To: <53ee2a62-7822-5457-e59f-e65e64a57019@infradead.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Geoff Levand , kexec@lists.infradead.org Cc: james.morse@arm.com, linux-arm-kernel@lists.infradead.org Hi Geoff, On Wednesday 23 November 2016 12:27 AM, Geoff Levand wrote: > Hi Pratyush, > > On 11/21/2016 08:32 PM, Pratyush Anand wrote: >> When "enable-dcache" is passed to the kexec() command line, kexec-tools >> passes this information to purgatory, which in turn enables cache during >> sha-256 verification. > > What's the point of this enable-dcache option? Why not just > always enable the cache if we can? As I have written in changelog of patch 1/2 "We are supporting only 4K and 64K page sizes. This code will not work if a hardware is not supporting at least one of these page sizes. Therefore, D-cache is disabled by default and enabled only when "enable-dcache" is passed to the kexec()." Although this is very unlikely that a hardware will support only 16K page sizes, however it is possible. Therefore, its better to keep it disabled by default. ~Pratyush _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec