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From: Anthony PERARD <anthony.perard@citrix.com>
To: Julien Grall <julien@xen.org>
Cc: "Stefano Stabellini" <sstabellini@kernel.org>,
	"Wei Liu" <wl@xen.org>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Ian Jackson" <ian.jackson@eu.citrix.com>,
	"George Dunlap" <george.dunlap@citrix.com>,
	"Julien Grall" <julien.grall@arm.com>,
	"Jan Beulich" <jbeulich@suse.com>,
	xen-devel@lists.xenproject.org,
	"Volodymyr Babchuk" <Volodymyr_Babchuk@epam.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [XEN PATCH v3 2/2] xen/arm: Configure early printk via Kconfig
Date: Wed, 11 Mar 2020 17:38:54 +0000	[thread overview]
Message-ID: <20200311173854.GK2152@perard.uk.xensource.com> (raw)
In-Reply-To: <a3bf47e1-2abb-f663-8f38-70c70d9c6114@xen.org>

On Wed, Mar 11, 2020 at 05:21:24PM +0000, Julien Grall wrote:
> On 11/03/2020 15:26, Anthony PERARD wrote:
> > On Wed, Mar 11, 2020 at 02:18:20PM +0000, Julien Grall wrote:
> > > > +config EARLY_UART_BASE_ADDRESS
> > > > +	depends on EARLY_PRINTK
> > > > +	hex "Early printk, physical base address of debug UART"
> > > > +	default 0x87e024000000 if EARLY_PRINTK_THUNDERX
> > > 
> > > You are allowing EARLY_PRINTK_THUNDERX to be selected on Arm32 platform but
> > > the address is above 4G. I suspect this would break randconfig build.
> > 
> > gcc doesn't seems to complain :-).
> 
> I was expecting GAS to throw an error because the 64-bit value does not fit
> in a 32-bit register. But... it looks like GAS will silently truncate the
> value to 0x24000000 :(.
> 	
> > (I mean "arm-none-eabi-gcc (Arch Repository) 9.2.0")
> > 
> > But I can have thunderx depends on arm_64.
> Is there a way to constrainst the address in Kconfig?

There is! I can add "range 0x0 0xffffffff if ARM_32".
But Kconfig doesn't say anything if a default value is too high, and
silently set the value to the maximum.
Still, it's better. I just need to add depends on ARM_64 for thunderx,
and that should be fine.
And that prevent users from setting a too hight value, as kconfig will
not accept a value outside the range.

Thanks,

-- 
Anthony PERARD

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  reply	other threads:[~2020-03-11 17:39 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-09 17:45 [Xen-devel] [XEN PATCH v3 0/2] xen/arm: Configure early printk via Kconfig Anthony PERARD
2020-03-09 17:45 ` [Xen-devel] [XEN PATCH v3 1/2] xen/arm: Rename all early printk macro Anthony PERARD
2020-03-11 13:57   ` Julien Grall
2020-03-11 14:46     ` Anthony PERARD
2020-03-12 20:18       ` Julien Grall
2020-03-13 23:01         ` Stefano Stabellini
2020-03-09 17:45 ` [Xen-devel] [XEN PATCH v3 2/2] xen/arm: Configure early printk via Kconfig Anthony PERARD
2020-03-11 14:18   ` Julien Grall
     [not found]     ` <20200311152613.GJ2152@perard.uk.xensource.com>
2020-03-11 17:21       ` Julien Grall
2020-03-11 17:38         ` Anthony PERARD [this message]
2020-03-12 20:16           ` Julien Grall
2020-03-13 23:12   ` Stefano Stabellini
2020-03-13 23:14     ` Stefano Stabellini
2020-03-17  9:36       ` Julien Grall
2020-03-17 17:51         ` Stefano Stabellini
2020-03-24 14:48           ` Anthony PERARD
2020-03-13 23:19     ` Julien Grall
2020-03-13 23:37       ` Julien Grall

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