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From: Sascha Hauer <s.hauer@pengutronix.de>
To: Oleksij Rempel <fishor@gmx.net>
Cc: Barebox List <barebox@lists.infradead.org>
Subject: Re: [PATCH 5/6] ARM: i.MX: external NAND boot: Leave icache disabled
Date: Wed, 19 Feb 2020 09:27:30 +0100	[thread overview]
Message-ID: <20200219082730.jwvsp3cdsoomdhwd@pengutronix.de> (raw)
In-Reply-To: <843b47cf-272e-3800-df85-9a2f9dcbee23@gmx.net>

On Wed, Feb 19, 2020 at 07:23:09AM +0100, Oleksij Rempel wrote:
> Am 18.02.20 um 16:37 schrieb Sascha Hauer:
> > It seems running from the NFC SRAM doesn't work with the instruction
> > cache enabled, it leads to corruptions on the i.MX27. We stumbled upon
> > this earlier and the solution at that time was to disable the
> > instruction cache in the NAND boot code. It is, however, more reliable
> > to just not enable the instruction cache in the first place.
> > This is not particularly nice as we have to ifdef this in generic code,
> > duplicate arm_cpu_lowlevel_init(), or call arm_cpu_lowlevel_init() later
> > when we are out of NFC SRAM. From the different bad solutions I chose
> > to ifdef the instruction cache away. It will be enabled later in the
> > common cache functions.
> 
> 
> Hm... is it possible that we have similar speculation issues as on i.MX6UL? The CPU was speculating
> in to IOMEM, caused cache poisoning/corruption and executed corrupted cache.

I don't know how much speculation an ARM9 processor does, but the end
result looks very similar. via JTAG I can see that the memory matches
my disassembly, just the CPU does something completely different.

Sascha

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  reply	other threads:[~2020-02-19  8:27 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-18 15:37 [PATCH 0/6] i.MX: Fix external NAND boot Sascha Hauer
2020-02-18 15:37 ` [PATCH 1/6] ARM: i.MX Phytec phycard i.MX27: get fdt in common init function Sascha Hauer
2020-02-18 15:37 ` [PATCH 2/6] ARM: i.MX Phytec phycard i.MX27: replace __naked with noinline Sascha Hauer
2020-02-18 15:37 ` [PATCH 3/6] ARM: i.MX Phytec phycore " Sascha Hauer
2020-02-18 15:37 ` [PATCH 4/6] ARM: i.MX: external NAND boot: remove unnecessary arguments from imx*_nand_load_image Sascha Hauer
2020-02-18 15:37 ` [PATCH 5/6] ARM: i.MX: external NAND boot: Leave icache disabled Sascha Hauer
2020-02-19  6:23   ` Oleksij Rempel
2020-02-19  8:27     ` Sascha Hauer [this message]
2020-02-19 11:53       ` Lucas Stach
2020-02-18 15:37 ` [PATCH 6/6] ARM: i.MX: external NAND boot: Fix passing boarddata Sascha Hauer

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