lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 23 Jan 2014 15:01:09 -0500 (EST) From: Nicolas Pitre <nico@...xnic.net> To: Russell King - ARM Linux <linux@....linux.org.uk> Cc: Wang Nan <wangnan0@...wei.com>, kexec@...ts.infradead.org, Eric Biederman <ebiederm@...ssion.com>, Andrew Morton <akpm@...ux-foundation.org>, Geng Hui <hui.geng@...wei.com>, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org, stable@...r.kernel.org Subject: Re: [PATCH 3/3] ARM: allow kernel to be loaded in middle of phymem On Thu, 23 Jan 2014, Russell King - ARM Linux wrote: > On Thu, Jan 23, 2014 at 02:15:07PM -0500, Nicolas Pitre wrote: > > On Wed, 22 Jan 2014, Wang Nan wrote: > > > > > This patch allows the kernel to be loaded at the middle of kernel awared > > > physical memory. Before this patch, users must use mem= or device tree to cheat > > > kernel about the start address of physical memory. > > > > > > This feature is useful in some special cases, for example, building a crash > > > dump kernel. Without it, kernel command line, atag and devicetree must be > > > adjusted carefully, sometimes is impossible. > > > > With CONFIG_PATCH_PHYS_VIRT the value for PHYS_OFFSET is determined > > dynamically by rounding down the kernel image start address to the > > previous 16MB boundary. In the case of a crash kernel, this might be > > cleaner to simply readjust __pv_phys_offset during early boot and call > > fixup_pv_table(), and then reserve away the memory from the previous > > kernel. That will let you access that memory directly (with gdb for > > example) and no pointer address translation will be required. > > We already have support in the kernel to ignore memory below the calculated > PHYS_OFFSET. See 571b14375019c3a66ef70d4d4a7083f4238aca30. Sure. Anyway what I'm suggesting above would require that the crash kernel be linked at a different virtual address for that to work. That's probably more trouble than simply mapping the otherwise still unmapped memory from the crashed kernel. Nicolas -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists