From: Tom Rini <trini@konsulko.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH 12/16] efi_loader: Add DCACHE_OFF support for arm64
Date: Tue, 2 Feb 2016 11:28:17 -0500 [thread overview]
Message-ID: <20160202162817.GA25786@bill-the-cat> (raw)
In-Reply-To: <20160202155517.GA25490@leverpostej>
On Tue, Feb 02, 2016 at 03:55:17PM +0000, Mark Rutland wrote:
> On Tue, Feb 02, 2016 at 03:45:10AM +0100, Alexander Graf wrote:
> > On arm64, boards can declare that they want to run with dcache disabled.
> >
> > However, uEFI guarantees to payloads that they're running with the dcache
> > enabled which on arm64 means that they can do unaligned accesses.
> >
> > To not leave those systems out of the door, let's handle the unaligned traps.
> > In the typical boot case, the OS will set up page tables and dcache itself
> > early on anyway once it's done talking with uEFI.
>
> This is not sufficient to emulate having caches enabled.
>
> There are other things which operate differently with the caches on
> (e.g. exclusives and/or atomics, which a compiler might generate
> implicitly).
>
> Likewise, cache-maintenance by Va (which you may require from the
> I-side) implicitly hazards against cacheable accesses, but not against
> non-cacheable accesses.
>
> There are almsot certainly other differences.
>
> Due to that, I don't think this is a good approach.
>
> Why can we not map memory using cacheable attributes in all cases?
I have a simpiler question perhaps, why can we not just say that this
support (in Kconfig that is) depends on !SYS_DACHE_OFF ? Yes, only ARC
as moved that symbol over to Kconfig but that's a relatively easy thing
to remedy. I assume that it being off on some systems is more of a
debug / bringup thing that needs to be circled back to rather than a
good hard requirement of the platform.
--
Tom
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next prev parent reply other threads:[~2016-02-02 16:28 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-02 2:44 [U-Boot] [PATCH 00/16] EFI payload / application support v3 Alexander Graf
2016-02-02 2:44 ` [U-Boot] [PATCH 01/16] disk/part.c: Expose list of available block drivers Alexander Graf
2016-02-03 3:31 ` Simon Glass
2016-02-02 2:45 ` [U-Boot] [PATCH 02/16] include/efi_api.h: Add more detailed API definitions Alexander Graf
2016-02-03 3:31 ` Simon Glass
2016-02-02 2:45 ` [U-Boot] [PATCH 03/16] efi_loader: Add PE image loader Alexander Graf
2016-02-02 12:54 ` Leif Lindholm
2016-02-02 17:49 ` Mark Rutland
2016-02-26 1:25 ` Alexander Graf
2016-02-03 3:31 ` Simon Glass
2016-02-02 2:45 ` [U-Boot] [PATCH 04/16] efi_loader: Add boot time services Alexander Graf
2016-02-02 14:47 ` Leif Lindholm
2016-02-26 1:00 ` Alexander Graf
2016-02-03 3:31 ` Simon Glass
2016-02-02 2:45 ` [U-Boot] [PATCH 05/16] efi_loader: Add console interface Alexander Graf
2016-02-03 3:31 ` Simon Glass
2016-02-02 2:45 ` [U-Boot] [PATCH 06/16] efi_loader: Add runtime services Alexander Graf
2016-02-03 3:31 ` Simon Glass
2016-02-02 2:45 ` [U-Boot] [PATCH 07/16] efi_loader: Add disk interfaces Alexander Graf
2016-02-03 3:31 ` Simon Glass
2016-02-02 2:45 ` [U-Boot] [PATCH 08/16] efi_loader: Add "bootefi" command Alexander Graf
2016-02-03 3:31 ` Simon Glass
2016-02-02 2:45 ` [U-Boot] [PATCH 09/16] efi_loader: Implement memory allocation and map Alexander Graf
2016-02-02 17:35 ` Leif Lindholm
2016-02-03 3:31 ` Simon Glass
2016-02-02 2:45 ` [U-Boot] [PATCH 10/16] arm64: Allow exceptions to return Alexander Graf
2016-02-02 2:45 ` [U-Boot] [PATCH 11/16] arm64: Allow EFI payload code to take exceptions Alexander Graf
2016-02-02 2:45 ` [U-Boot] [PATCH 12/16] efi_loader: Add DCACHE_OFF support for arm64 Alexander Graf
2016-02-02 15:55 ` Mark Rutland
2016-02-02 16:28 ` Tom Rini [this message]
2016-02-02 16:58 ` Alexander Graf
2016-02-02 2:45 ` [U-Boot] [PATCH 13/16] efi_loader: hook up in build environment Alexander Graf
2016-02-03 3:31 ` Simon Glass
2016-02-02 2:45 ` [U-Boot] [PATCH 14/16] efi_loader: Add distro boot script for removable media Alexander Graf
2016-02-02 17:52 ` Leif Lindholm
2016-02-26 1:29 ` Alexander Graf
2016-02-03 10:36 ` Leif Lindholm
2016-02-03 15:53 ` Alexander Graf
2016-02-04 4:11 ` Simon Glass
2016-02-02 2:45 ` [U-Boot] [PATCH 15/16] efi_loader: Add README section in README.efi Alexander Graf
2016-02-03 3:31 ` Simon Glass
2016-02-02 2:45 ` [U-Boot] [PATCH 16/16] efi_loader: Add MAINTAINERS entry Alexander Graf
2016-02-03 3:31 ` Simon Glass
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