From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Wed, 14 Dec 2016 13:44:57 +0000 Subject: [PATCH 1/2] arm64: Add enable/disable d-cache support for purgatory In-Reply-To: <3a6ac655-bfa6-0d90-6351-731ce36e99eb@redhat.com> References: <7a4866b928c0905ec1074dce1bfc7984c968a58a.1479788404.git.panand@redhat.com> <5838834D.90205@arm.com> <9a79b666-7990-2a23-2d74-52b3317ce272@redhat.com> <58512A01.70101@arm.com> <20161214113701.GE17982@leverpostej> <3a6ac655-bfa6-0d90-6351-731ce36e99eb@redhat.com> Message-ID: <20161214134457.GJ17982@leverpostej> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On Wed, Dec 14, 2016 at 05:51:05PM +0530, Pratyush Anand wrote: > > On Wednesday 14 December 2016 05:07 PM, Mark Rutland wrote: > >I see in an earlier message that the need for sha256 was being discussed > >in another thread. Do either of you happen to have a pointer to that. > > patch 0/2 of this series. AFAICT, that just says the the existing sha256 check is slow, not *why* a sha256 check of some description is necessary. I'm still at a loss as to why it is considered necessary, rather than being a debugging aid or sanity check. > >To me, it seems like it doesn't come with much benefit for the kdump > >case given that's best-effort anyway, and as above the verification code > >could have been be corrupted. In the non-kdump case it's not strictly > >necessary and seems like a debugging aid rather than a necessary piece > >of functionality -- if that's the case, a 20 second delay isn't the end > >of the world... > > Even for the non-kdump ie `kexec -l` case we do not have a > functionality to bypass sha verification in kexec-tools. --lite > option with the kexec-tools was discouraged and not accepted. Ok. Do you have a pointer to the thread regarding that, for context? > So,it is 20s for both `kexec -l` and `kexec -p`. Well, unless we can have a --{no-,}sha-check, and make the default NO for arm64. > Also other arch like x86_64 takes negligible time in sha verification. That's certainly an argument for not changing the other architectures, but given it's slow for arm64, we could have a different default... Thanks, Mark.