| Message ID | 1357918457-20469-7-git-send-email-will.deacon@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Will, On 01/11/2013 10:34 AM, Will Deacon wrote: > ARM_VIRT_EXT is a property of CPU_V7, but does not adversely affect > other CPUs that can be built into the same kernel image (i.e. ARMv6+). > > This patch defaults ARM_VIRT_EXT to y if CPU_V7, allowing hypervisors > such as KVM to make better use of the option and being able to rely > on hyp-mode boot support. [...] > @@ -640,11 +641,6 @@ config ARM_VIRT_EXT > use of this feature. Refer to Documentation/arm/Booting for > details. > > - It is safe to enable this option even if the kernel may not be > - booted in HYP mode, may not have support for the > - virtualization extensions, or may be booted with a > - non-compliant bootloader. Why take this out? [...] Regards, Christopher
On Fri, Jan 11, 2013 at 03:42:40PM +0000, Christopher Covington wrote: > Hi Will, Hello, > On 01/11/2013 10:34 AM, Will Deacon wrote: > > ARM_VIRT_EXT is a property of CPU_V7, but does not adversely affect > > other CPUs that can be built into the same kernel image (i.e. ARMv6+). > > > > This patch defaults ARM_VIRT_EXT to y if CPU_V7, allowing hypervisors > > such as KVM to make better use of the option and being able to rely > > on hyp-mode boot support. > > [...] > > > @@ -640,11 +641,6 @@ config ARM_VIRT_EXT > > use of this feature. Refer to Documentation/arm/Booting for > > details. > > > > - It is safe to enable this option even if the kernel may not be > > - booted in HYP mode, may not have support for the > > - virtualization extensions, or may be booted with a > > - non-compliant bootloader. > > Why take this out? I just removed that last paragraph because it's not user-selectable anymore, so this comment about enabling the option is redundant. I could remove all of the help text, but we have it for some other options that are selected automatically and it has a pointer to some documentation too. Will
On 01/11/2013 11:43 AM, Will Deacon wrote: > On Fri, Jan 11, 2013 at 03:42:40PM +0000, Christopher Covington wrote: >> Hi Will, > > Hello, > >> On 01/11/2013 10:34 AM, Will Deacon wrote: >>> ARM_VIRT_EXT is a property of CPU_V7, but does not adversely affect >>> other CPUs that can be built into the same kernel image (i.e. ARMv6+). >>> >>> This patch defaults ARM_VIRT_EXT to y if CPU_V7, allowing hypervisors >>> such as KVM to make better use of the option and being able to rely >>> on hyp-mode boot support. >> >> [...] >> >>> @@ -640,11 +641,6 @@ config ARM_VIRT_EXT >>> use of this feature. Refer to Documentation/arm/Booting for >>> details. >>> >>> - It is safe to enable this option even if the kernel may not be >>> - booted in HYP mode, may not have support for the >>> - virtualization extensions, or may be booted with a >>> - non-compliant bootloader. >> >> Why take this out? > > I just removed that last paragraph because it's not user-selectable anymore, > so this comment about enabling the option is redundant. I could remove all > of the help text, but we have it for some other options that are selected > automatically and it has a pointer to some documentation too. It's not a big deal, but that paragraph helped me understand the (lack of) ramifications for v7 CPU's without the virtualization extensions, and I figure it might still be helpful for others as well. Christopher
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index 3fd629d..025d173 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -629,8 +629,9 @@ config ARM_THUMBEE make use of it. Say N for code that can run on CPUs without ThumbEE. config ARM_VIRT_EXT - bool "Native support for the ARM Virtualization Extensions" - depends on MMU && CPU_V7 + bool + depends on MMU + default y if CPU_V7 help Enable the kernel to make use of the ARM Virtualization Extensions to install hypervisors without run-time firmware @@ -640,11 +641,6 @@ config ARM_VIRT_EXT use of this feature. Refer to Documentation/arm/Booting for details. - It is safe to enable this option even if the kernel may not be - booted in HYP mode, may not have support for the - virtualization extensions, or may be booted with a - non-compliant bootloader. - config SWP_EMULATE bool "Emulate SWP/SWPB instructions" depends on !CPU_USE_DOMAINS && CPU_V7
ARM_VIRT_EXT is a property of CPU_V7, but does not adversely affect other CPUs that can be built into the same kernel image (i.e. ARMv6+). This patch defaults ARM_VIRT_EXT to y if CPU_V7, allowing hypervisors such as KVM to make better use of the option and being able to rely on hyp-mode boot support. Signed-off-by: Will Deacon <will.deacon@arm.com> --- arch/arm/mm/Kconfig | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-)