> On Oct 10, 2015, at 00:10, Russell King - ARM Linux <[email protected]> > wrote: > > On Fri, Oct 09, 2015 at 11:55:09PM +0800, yalin wang wrote: >> Add support for initrd on ARM arch, in case >> mem= boot option change the memory size or the initrd are >> not placed in low memory region, we need copy the initrd >> to low memory region. >> >> Signed-off-by: yalin wang <[email protected]> >> --- >> arch/arm/include/asm/fixmap.h | 1 + >> arch/arm/kernel/setup.c | 72 >> +++++++++++++++++++++++++++++++++++++++++++ >> 2 files changed, 73 insertions(+) >> >> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h >> index 58cfe9f..18ad90f 100644 >> --- a/arch/arm/include/asm/fixmap.h >> +++ b/arch/arm/include/asm/fixmap.h >> @@ -10,6 +10,7 @@ >> >> enum fixed_addresses { >> FIX_EARLYCON_MEM_BASE, >> + FIX_RELOCATE_INITRD, >> __end_of_permanent_fixed_addresses, >> >> FIX_KMAP_BEGIN = __end_of_permanent_fixed_addresses, >> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c >> index 20edd34..4260d59 100644 >> --- a/arch/arm/kernel/setup.c >> +++ b/arch/arm/kernel/setup.c >> @@ -811,6 +811,77 @@ static void __init request_standard_resources(const >> struct machine_desc *mdesc) >> request_resource(&ioport_resource, &lp2); >> } >> >> +#if defined(CONFIG_BLK_DEV_INITRD) && defined(CONFIG_MMU) >> +/* >> + * Relocate initrd if it is not completely within the linear mapping. >> + * This would be the case if mem= cuts out all or part of it >> + * or the initrd are not in low mem region place. >> + */ >> +static void __init relocate_initrd(void) >> +{ >> + phys_addr_t orig_start = __virt_to_phys(initrd_start); >> + phys_addr_t orig_end = __virt_to_phys(initrd_end); > > If initrd_start or initrd_end are outside of the lowmem region, it's > quite possible for these to return incorrect physical addresses. > The generic kernel's idea of using virtual addresses for the initrd > stuff is painfully wrong IMHO. > > The unfortunate thing is that the DT code propagates this stuff: > > initrd_start = (unsigned long)__va(start); > initrd_end = (unsigned long)__va(end); > > and even this can give wrong results for the virtual address when the > physical is outside of lowmem. For addresses outside of lowmem, > __virt_to_phys(__va(start)) is not guaranteed to return 'start'. > > This is why I've said that if we want to support ramdisks outside of > the lowmem mapping, we need to get rid of the initrd_start/initrd_end > virtual addresses. > > I'm sorry, but we need much wider code changes before we can cope with > this. > >> + phys_addr_t ram_end = memblock_end_of_DRAM(); >> + phys_addr_t new_start; >> + phys_addr_t src; >> + unsigned long size, to_free = 0; >> + unsigned long slop, clen, p; >> + void *dest; >> + >> + if (orig_end <= memblock_get_current_limit()) >> + return; >> + >> + /* >> + * Any of the original initrd which overlaps the linear map should >> + * be freed after relocating. > > How does this work? The code in arm_memblock_init() will have already > reserved the physical addresses for the ramdisk: > > memblock_reserve(phys_initrd_start, phys_initrd_size); > > So any new allocation shouldn't overlap the existing ramdisk - unless > this is wrong. > i see, i will send a V2 patch for review .
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