From mboxrd@z Thu Jan  1 00:00:00 1970
From: Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH v7 20/25] ACPI / APEI: Use separate fixmap pages for
 arm64 NMI-like notifications
Date: Thu, 31 Jan 2019 14:38:42 +0100
Message-ID: <20190131133842.GK6749@zn.tnic>
References: <20181203180613.228133-1-james.morse@arm.com>
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To: James Morse <james.morse@arm.com>
Cc: Rafael Wysocki <rjw@rjwysocki.net>, Tony Luck <tony.luck@intel.com>, Fan Wu <wufan@codeaurora.org>, linux-mm@kvack.org, Marc Zyngier <marc.zyngier@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Dongjiu Geng <gengdongjiu@huawei.com>, linux-acpi@vger.kernel.org, Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, Len Brown <lenb@kernel.org>
List-Id: linux-acpi@vger.kernel.org

On Wed, Jan 23, 2019 at 06:33:02PM +0000, James Morse wrote:
> Was the best I had, but this trips the BUILD_BUG() too early.
> With it, x86 BUILD_BUG()s. With just the -1 the path gets pruned out, and there
> are no 'sdei' symbols in the object file.
> 
> ...at this point, I stopped caring!

Yah, you said it: __end_of_fixed_addresses will practically give you the
BUG behavior:

        if (idx >= __end_of_fixed_addresses) {
                BUG();
                return;
        }

and ARM64 does the same.

> We already skip registering notifiers if the kconfig option wasn't selected.
> 
> We can't catch this at compile time, as the dead-code elimination seems to
> happen in multiple passes.
> 
> I'll switch the SDEI ones to __end_of_fixed_addresses, as both architectures
> BUG() when they see this.

Right.

Thx.

-- 
Regards/Gruss,
    Boris.

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