linux-kernel - Re: [PATCH 12/12] efi: make const array 'apple' static

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Message-ID: <20180309080428.atur6wcbb6vtonhz@gmail.com>
Date:   Fri, 9 Mar 2018 09:04:28 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     linux-efi@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Colin Ian King <colin.king@...onical.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 12/12] efi: make const array 'apple' static


* Ard Biesheuvel <ard.biesheuvel@...aro.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.

Thanks,

	Ingo