We are trying to reduce the memory allocation needed for kdump kernel. We want to reserve less than 32M for kdump kernel if possible. We are able to get ~14M saving by the proposed change. Below are the numbers before and after the proposed change:
With 48 bit physical address and 30 bit section size: -------------------------------------------------------------------- Memory: 23052K/49152K available (3460K kernel code, 296K rwdata, 2436K rodata, 204K init, 179K bss, 26100K reserved, 0K cma-reserved) With 43 bit physical address and 27bit section size: -------------------------------------------------------------------- Memory: 37284K/49152K available (3596K kernel code, 296K rwdata, 2408K rodata, 208K init, 173K bss, 11868K reserved, 0K cma-reserved) Thanks, -Nikunj ________________________________________ From: Catalin Marinas <catalin.mari...@arm.com> Sent: Tuesday, July 3, 2018 7:56 AM To: Nikunj Kela (nkela) Cc: Will Deacon; xe-ker...@external.cisco.com; linux-kernel@vger.kernel.org; linux-arm-ker...@lists.infradead.org Subject: Re: [PATCH 2/2] arm64: add support for 43bit physical address On Mon, Jul 02, 2018 at 02:04:51PM -0700, Nikunj Kela wrote: > This patch adds support for 43bit physical address. Additionally, > this patch adds support for 27bit section size. This is useful in > reducing kernel memory usage. One usecase is in kdump kernel. Some numbers please. -- Catalin
