linux-kernel - Re: [PATCH v6 1/9] efi: Use early_mem*() instead of early

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Message-ID: <20140623135446.GG28489@olila.local.net-space.pl>
Date:	Mon, 23 Jun 2014 15:54:46 +0200
From:	Daniel Kiper <daniel.kiper@...cle.com>
To:	Jan Beulich <JBeulich@...e.com>
Cc:	andrew.cooper3@...rix.com, david.vrabel@...rix.com,
	ian.campbell@...rix.com, stefano.stabellini@...citrix.com,
	jeremy@...p.org, matt.fleming@...el.com, x86@...nel.org,
	tglx@...utronix.de, xen-devel@...ts.xenproject.org,
	boris.ostrovsky@...cle.com, konrad.wilk@...cle.com,
	eshelton@...ox.com, mingo@...hat.com, mjg59@...f.ucam.org,
	linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
	hpa@...or.com, tony.luck@...el.com, fenghua.yu@...el.com,
	linux-ia64@...r.kernel.org
Subject: Re: [PATCH v6 1/9] efi: Use early_mem*() instead of early_io*()

I am CC'ing IA-64 guys.

On Mon, Jun 23, 2014 at 08:19:00AM +0100, Jan Beulich wrote:
> >>> On 20.06.14 at 23:29, <daniel.kiper@...cle.com> wrote:
> > --- a/drivers/firmware/efi/efi.c
> > +++ b/drivers/firmware/efi/efi.c
> > @@ -298,7 +298,7 @@ int __init efi_config_init(efi_config_table_type_t *arch_tables)
> >  			if (table64 >> 32) {
> >  				pr_cont("\n");
> >  				pr_err("Table located above 4GB, disabling EFI.\n");
> > -				early_iounmap(config_tables,
> > +				early_memunmap(config_tables,
> >  					       efi.systab->nr_tables * sz);
> >  				return -EINVAL;
> >  			}
> > @@ -314,7 +314,7 @@ int __init efi_config_init(efi_config_table_type_t *arch_tables)
> >  		tablep += sz;
> >  	}
> >  	pr_cont("\n");
> > -	early_iounmap(config_tables, efi.systab->nr_tables * sz);
> > +	early_memunmap(config_tables, efi.systab->nr_tables * sz);
> >
> >  	set_bit(EFI_CONFIG_TABLES, &efi.flags);
> >
>
> If these two changes are really deemed necessary (there's the
> implied assumption currently in place that early_iounmap() can
> undo early_memremap() mappings), then ia64 will need a
> definition added for early_memunmap() or its build will break.

I know that early_memunmap() == early_iounmap() in general. However,
I think that it is less confusing if use relevant functions in pairs
(i.e. early_memremap() with early_memunmap(), ...) than mix them up.

We have following choices here:
  - leave early_iounmap() as is in drivers/firmware/efi/efi.c
    (arch/x86/platform/efi/efi.c:early_iounmap() -> early_memunmap()
    changes should be left as is),
  - include asm/early_ioremap.h in arch/ia64/include/asm/io.h
    (as I can see the same think is done for x86 and arm64).

I prefer second solution but I do not insist.

Daniel
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