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From: Ingo Molnar <mingo@kernel.org>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-efi@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	Colin Ian King <colin.king@canonical.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 12/12] efi: make const array 'apple' static
Date: Fri, 9 Mar 2018 09:31:15 +0100	[thread overview]
Message-ID: <20180309083115.mvnrtvukc7sqe2i2@gmail.com> (raw)
In-Reply-To: <CAKv+Gu86v9-Cj3bxEPWXCMRnE7S76kGdu7to3cOoLMgTTcH_xg@mail.gmail.com>


* Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:

> On 9 March 2018 at 08:04, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > * Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> >
> >> > Also, would it make sense to rename it to something more descriptive like
> >> > "apple_unicode_str[]" or so?
> >> >
> >> > Plus an unicode string literal initializer would be pretty descriptive as well,
> >> > instead of the weird looking character array, i.e. something like:
> >> >
> >> >   static efi_char16_t const apple_unicode_str[] = u"Apple";
> >> >
> >> > ... or so?
> >> >
> >>
> >> is u"xxx" the same as L"xxx"?
> >
> > So "L" literals map to wchar_t, which wide character type is implementation
> > specific IIRC, could be 16-bit or 32-bit wide.
> >
> > u"" literals OTOH are specified by the C11 spec to be char16_t, i.e. 16-bit wide
> > characters - which I assume is the EFI type as well?
> >
> >> In any case, this is for historical reasons: at some point (and I
> >> don't remember the exact details) we had a conflict at link time with
> >> objects using 4 byte wchar_t, so we started using this notation to be
> >> independent of the size of wchar_t. That issue no longer exists so we
> >> should be able to get rid of this.
> >
> > Yes, my guess is that those problems were due to L"xyz" mapping to wchar_t and
> > having a different type in the kernel build and the host build side - but u"xyz"
> > should solve that.
> >
> 
> Excellent!

Please double check the generated code though, all of this is from memory.

> Do you mind taking this patch as is? I will follow up with a patch
> that updates all occurrences of this pattern (we have a few of them),
> i.e., use u"" notation and move them to file scope.

Sure, done!

Thanks,

	Ingo

  parent reply	other threads:[~2018-03-09  8:31 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-08  8:00 [GIT PULL 00/12] first batch of EFI changes for v4.17 Ard Biesheuvel
2018-03-08  8:00 ` [PATCH 01/12] efi/arm*: Only register page tables when they exist Ard Biesheuvel
2018-03-08  8:00 ` [PATCH 02/12] efi/apple-properties: Device core takes care of empty properties Ard Biesheuvel
2018-03-08  8:00 ` [PATCH 03/12] efi/arm*: Stop printing addresses of virtual mappings Ard Biesheuvel
2018-03-08  8:00 ` [PATCH 04/12] efi/x86: Fix trailing semicolons Ard Biesheuvel
2018-03-08  8:00 ` [PATCH 05/12] efi: arm64: Check whether x18 is preserved by runtime services calls Ard Biesheuvel
2018-03-08  8:00 ` [PATCH 06/12] x86: efi: Replace GFP_ATOMIC with GFP_KERNEL in efi_query_variable_store Ard Biesheuvel
2018-03-09  7:54   ` Ingo Molnar
2018-03-08  8:00 ` [PATCH 07/12] efi: Use efi_mm in x86 as well as ARM Ard Biesheuvel
2018-03-09  7:40   ` Ingo Molnar
2018-03-09  8:37     ` Prakhya, Sai Praneeth
2018-03-09  9:56       ` Ard Biesheuvel
2018-03-08  8:00 ` [PATCH 08/12] x86/efi: Replace efi_pgd with efi_mm.pgd Ard Biesheuvel
2018-03-08  8:00 ` [PATCH 09/12] x86/efi: Use efi_switch_mm() rather than manually twiddling with %cr3 Ard Biesheuvel
2018-03-08  8:00 ` [PATCH 10/12] efi: reorder pr_notice() with add_device_randomness() call Ard Biesheuvel
2018-03-08  8:00 ` [PATCH 11/12] efi/apple-properties: Use memremap() instead of ioremap() Ard Biesheuvel
2018-03-08  8:00 ` [PATCH 12/12] efi: make const array 'apple' static Ard Biesheuvel
2018-03-08 11:05   ` Joe Perches
2018-03-09  7:43     ` Ard Biesheuvel
2018-03-09  7:44       ` Ard Biesheuvel
2018-03-09  9:37         ` Joe Perches
2018-03-09  7:47   ` Ingo Molnar
2018-03-09  7:52     ` Ard Biesheuvel
2018-03-09  8:04       ` Ingo Molnar
2018-03-09  8:07         ` Ard Biesheuvel
2018-03-09  8:19           ` Ard Biesheuvel
2018-03-09  8:31           ` Ingo Molnar [this message]
2018-03-09  8:29     ` Lukas Wunner
2018-03-09  8:33       ` Ard Biesheuvel

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