-----Original Message-----
From: Marc Zyngier [mailto:marc.zyngier at arm.com]
Sent: Thursday, July 23, 2015 7:44 AM
To: Yoder Stuart-B08248; Catalin Marinas; Will Deacon
Cc: linux-arm-kernel at lists.infradead.org; Newton Peter-RA3823
Subject: Re: [RFC] arm64: defconfig: enable 48-bit VA by default

On 22/07/15 20:49, Stuart Yoder wrote:

quoted

Catalin/Will,

This is not a patch mean to be applied, but a query about whether there
is any reason to not enable 48-bit VA by default in the arm64 defconfig.

The Freescale LS2085A physical memory map requires 48-bit VA in Linux for the
reasons mentioned in [1].

Based on the comment in [1] by Catalin, it seems that the intent
is to turn this on by default.

Is there any issues anyone sees with a patch that does this:

diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index 4e17e7e..5acf75d 100644

@@ -47,6 +47,7 @@ CONFIG_ARCH_ZYNQMP=y
 CONFIG_PCI=y
 CONFIG_PCI_MSI=y
 CONFIG_PCI_XGENE=y
+CONFIG_ARM64_VA_BITS_48=y
 CONFIG_SMP=y
 CONFIG_PREEMPT=y
 CONFIG_KSM=y

Thanks,
Stuart

[1] https://www.marc.info/?l=linux-arm-kernel&m=140965303205473&w=1

Is that still a requirement now that our idmap can use 4 levels (as part
of dd006da)?

Thanks for the pointer... it looks like the patch series you referenced
solves the issue, so the defconfig change is not needed.  We're currently
on 4.0, and I guess need to get to 4.1.

Thanks,
Stuart