From mboxrd@z Thu Jan 1 00:00:00 1970 From: f.fainelli@gmail.com (Florian Fainelli) Date: Tue, 29 Aug 2017 09:51:14 -0700 Subject: ARM64 kernel Image size limitations? In-Reply-To: References: <02d56481-bba0-fd32-17d8-9f3760d09148@gmail.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 08/29/2017 01:15 AM, Ard Biesheuvel wrote: > On 28 August 2017 at 22:24, Florian Fainelli wrote: >> (fixed Will's address, apologies) >> >> On 08/28/2017 01:01 PM, Ard Biesheuvel wrote: >>> Hi, >>> >>> On 28 August 2017 at 20:55, Florian Fainelli wrote: >>>> Hi, >>>> >>>> I have been fighting with a reasonably large kernel Image: 46MB and >>>> found unable to boot it. This is on v4.13-rc6, but I could go back as >>>> far as v4.9~ish. It is so big, because it's got some debugging enabled, >>>> and the initramfs compression is disabled, but still that ought to be >>>> possible. >>>> >>>> After some experimentation I found that the breaking size is somewhere >>>> around 33MB total for arch/arm64/boot/Image and when that happens, I get >>>> the following backtrace which suggests that there is some memory >>>> corruption of some kind (or so it seems to me), other experiments >>>> indicated that the backtrace may point back to where the bootloader had >>>> set up its exception vector. I am fairly confident that the bootloader >>>> is not responsible for corrupting the Image that is loaded. >>>> >>>> Is there such a size limitation or am I possibly tripping over something >>>> else? >>>> >>> >>> What boot environment are you using? Is it possible the DTB is copied >>> on top of the kernel by the boot loader? >> >> Bootloader is BOLT (Broadcom's own implementation, has PSCI and is >> capable of doing FDT live patching), and yes the DTB is provided by the >> bootloader at an address higher than the kernel. >> >> Physical offset of the RAM on this platform is 0, so the load is going >> to be at PA 0x80000, 0x80000 + size (35MB) = 0x2280000, DTB is placed at >> 0x771f000 and is 0x90ef bytes. >> > > Could you try to dump __log_buf from gdb? Silly me, this is a bootloader limitation, unlike what I thought the load address is not at PA 0, it is at PA 0x06FFC000 and there is only ~34MB worth of space available, mayhem ensues. Thanks! -- Florian