Re: [PATCH] ARM: tegra: add kexec support to defconfig

[Thierry Reding <thierry.reding-RM9K5IK7kjKj5M59NBduVrNAH6kLmebB@public.gmane.org>]

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On Thu, Jan 03, 2013 at 02:18:27PM -0700, Stephen Warren wrote:
> On 01/03/2013 02:05 PM, Thierry Reding wrote:
> > On Wed, Jan 02, 2013 at 02:12:21PM -0700, Stephen Warren wrote:
> >> From: Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> >> 
> >> Signed-off-by: Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> --- 
> >> arch/arm/configs/tegra_defconfig |    1 + 1 file changed, 1
> >> insertion(+)
> >> 
> >> diff --git a/arch/arm/configs/tegra_defconfig
> >> b/arch/arm/configs/tegra_defconfig index 742dc41..e621603 100644 
> >> --- a/arch/arm/configs/tegra_defconfig +++
> >> b/arch/arm/configs/tegra_defconfig @@ -34,6 +34,7 @@
> >> CONFIG_AEABI=y CONFIG_HIGHMEM=y CONFIG_ZBOOT_ROM_TEXT=0x0 
> >> CONFIG_ZBOOT_ROM_BSS=0x0 +CONFIG_KEXEC=y CONFIG_CPU_FREQ=y 
> >> CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y CONFIG_CPU_IDLE=y
> > 
> > Interesting. What do you plan to use this for? kdump?
> 
> I plan to burn a kernel (and a small stub, and a DTB) into flash
> instead of U-Boot, and hence not have to rely on any bootloader.

Why does that require kexec support?

> Even ignoring that, a quick scp of a new kernel to a target followed
> by a kexec is faster than rebooting all the way through U-Boot's
> slower Ethernet support to boot a new kernel.

That sounds like an interesting approach. I wonder if this actually
works with the current state of drivers in mainline. Sounds like this
could speed up development quite a bit by avoiding full reboots.

Thierry

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