Messages in this thread | | | Date | Mon, 03 Jan 2011 13:20:39 +0100 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH 02/15] x86: Add device tree support |
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Grant Likely wrote: >> +extern char cmd_line[COMMAND_LINE_SIZE]; >> +/* This number is used when no interrupt has been assigned */ >> +#define NO_IRQ (-1) > > 0 means NO_IRQ on x86 and most architectures. I will change this when > I pick up the patch.
cat /proc/interrupts CPU0 0: 40 IO-APIC-edge timer
>> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c >> index 577d06b..26f2c9a 100644 >> --- a/arch/x86/kernel/setup.c >> +++ b/arch/x86/kernel/setup.c >> @@ -113,6 +113,7 @@ >> #endif >> #include <asm/mce.h> >> #include <asm/alternative.h> >> +#include <asm/prom.h> >> >> /* >> * end_pfn only includes RAM, while max_pfn_mapped includes all e820 entries. >> @@ -445,6 +446,9 @@ static void __init parse_setup_data(void) >> case SETUP_E820_EXT: >> parse_e820_ext(data); >> break; >> + case SETUP_DTB: >> + add_dtb(pa_data); >> + break; > > Why is the physical address being passed in when the virtual address > is needed to be stored in initial_boot_params by add_dtb()?
add_dtb() changes it via phys_to_virt() so it is stored as virtual. I can't touch this memory that early in the boot process so it is passed as phys. phys_to_virt() isn't working (yet) so you need a fixmap or an early_ioremap(). Earlier I used the device tree very late so the phys_to_virt() memory was working.
Later in the series add_dtb() stores it in a custom u64 variable because I might have to use the built-in dtb, I have to relocate the dtb (so the boot loader does not have to care about kernel's memory layout) and I have to use it "early" so I create a fixmap for it.
The dtb is not usable before the ->get_config() hook (x86_dtb_get_config, patch #5) is called. After that initial_boot_params is set and can be used.
>> default: >> break; >> } >> -- >> 1.7.3.2
Sebastian
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