linux-kernel - Re: [PATCH] arm: export memblock_reserve()d regions via /proc/iomem

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Message-ID: <20190921145138.GN25745@shell.armlinux.org.uk>
Date:   Sat, 21 Sep 2019 15:51:38 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Yu Chen <33988979@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        yu.chen3@....com.cn
Subject: Re: [PATCH] arm: export memblock_reserve()d regions via /proc/iomem

On Sat, Sep 21, 2019 at 09:02:49PM +0800, Yu Chen wrote:
> From: Yu Chen <yu.chen3@....com.cn>
> 
> memblock reserved regions are not reported via /proc/iomem on ARM, kexec's
> user-space doesn't know about memblock_reserve()d regions and thus
> possible for kexec to overwrite with the new kernel or initrd.

Many reserved regions come from the kernel allocating memory during
boot.  We don't want to prevent kexec re-using those regions.

> [    0.000000] Booting Linux on physical CPU 0xf00
> [    0.000000] Linux version 4.9.115-rt93-dirty (yuchen@...alhost.localdomain) (gcc version 6.2.0 (ZTE Embsys-TSP V3.07.2
> 0) ) #62 SMP PREEMPT Fri Sep 20 10:39:29 CST 2019
> [    0.000000] CPU: ARMv7 Processor [410fc075] revision 5 (ARMv7), cr=30c5387d
> [    0.000000] CPU: div instructions available: patching division code
> [    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
> [    0.000000] OF: fdt:Machine model: LS1021A TWR Board
> [    0.000000] INITRD: 0x80f7f000+0x03695e40 overlaps in-use memory region - disabling initrd

Is the overlapping region one that is marked as reserved in DT?
Where is the reserved region that overlaps the initrd coming from?

Thanks.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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