From: Sascha Hauer <s.hauer@pengutronix.de>
To: Michael Tretter <m.tretter@pengutronix.de>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH v3 1/2] ARM: mmu64: allow to disable null pointer trap on zero page
Date: Thu, 22 Oct 2020 09:31:19 +0200 [thread overview]
Message-ID: <20201022073119.GN26805@pengutronix.de> (raw)
In-Reply-To: <20201021145140.597728-1-m.tretter@pengutronix.de>
On Wed, Oct 21, 2020 at 04:51:39PM +0200, Michael Tretter wrote:
> Barebox uses the zero page to trap NULL pointer dereferences. However,
> if the SDRAM starts at address 0x0, this makes the first page of the
> SDRAM inaccessible and makes it impossible to load images to offset 0x0
> in the SDRAM.
>
> Trapping NULL pointer dereferences on such systems is still desirable.
> Therefore, add a function to disable the traps if accessing the zero
> page is necessary and to re-enable the traps after the access is done.
>
> The zero_page_memcpy function simplifies copying to the SDRAM, because
> this is the most common required functionality, but memtest also
> accesses the zero page and does not use memcpy.
>
> Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Applied, thanks
Sascha
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prev parent reply other threads:[~2020-10-22 7:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-21 14:51 Michael Tretter
2020-10-21 14:51 ` [PATCH v3 2/2] uimage: disable zero page when loading to SDRAM at address 0x0 Michael Tretter
2020-10-22 7:31 ` Sascha Hauer [this message]
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