On Tuesday 14 August 2012, Catalin Marinas wrote: > +The AArch64 exception model is made up of a number of exception levels > +(EL0 - EL3), with EL0 and EL1 having a secure and a non-secure > +counterpart. EL2 is the hypervisor level and exists only in non-secure > +mode. EL3 is the highest priority level and exists only in secure mode. I'm always confused by a description like this. It sounds like you cannot have a hypervisor if you have code running in secure mode in EL3. What I instead understand is that you enter non-secure mode by going from EL3 into EL2. > +2. Setup the device tree > +------------------------- > + > +Requirement: MANDATORY > + > +The device tree blob (dtb) must be no bigger than 2 megabytes in size > +and placed at a 2-megabyte boundary within the first 512 megabytes from > +the start of the kernel image. This is to allow the kernel to map the > +blob using a single section mapping in the initial page tables. I've seen people put firmware for some peripherals into the device tree, so that a device driver can grab a blob from there and load it into the device, rather than calling request_firmware() which would fail if the OS running on the system does not contain the blob. If such firmware is too large, you end up violating the 2 MB limit you impose here. Should we keep that limit and declare those use cases as invalid, or should we try to make the boot protocol more flexible? > diff --git a/arch/arm64/include/asm/setup.h b/arch/arm64/include/asm/setup.h > new file mode 100644 > index 0000000..d766493 > --- /dev/null > +++ b/arch/arm64/include/asm/setup.h > @@ -0,0 +1,26 @@ > +#ifndef __ASM_SETUP_H > +#define __ASM_SETUP_H > + > +#include <linux/types.h> > + > +#define COMMAND_LINE_SIZE 1024 > + > +#endif Is this necessary? The asm-generic version of this file allows 512 bytes, which seems plenty. > +unsigned int processor_id; > +EXPORT_SYMBOL(processor_id); > + > +unsigned int elf_hwcap __read_mostly; > +EXPORT_SYMBOL(elf_hwcap); EXPORT_SYMBOL_GPL? Neither of these looks like they should be used in drivers. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
