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a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1748636919; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=V683jXcvBO/wNHAZuQXuIAcraBnYtRvfHmOlvfeKHUA=; b=vRUObJAvyUV8tetCrYJ9QxCbGrleRnbzLbScu36vYFTLrxCgEgObgvGeBl4a8F0Yu52rB9 tBDXeLbvy/S7VYp489G4kHklWdiAr3gBuc/XfrBknpmmCuJnJhbYJPlWTUEiyRKNoKhA5h 1dyScj+vRyp2Hgr+TZ3uYWAlQmsD42E= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1748636919; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=V683jXcvBO/wNHAZuQXuIAcraBnYtRvfHmOlvfeKHUA=; b=AUc3mLC5ImAbsKHOPaSiivAFkw0ONXDoPjlYRoLEfdtOxryA8PHrHKlN6MMP/qm9PgNBgi cxWqV+YWIPqHf3Aw== Date: Fri, 30 May 2025 22:28:39 +0200 From: Jiri Bohac To: Baoquan He , Vivek Goyal , Dave Young , kexec@lists.infradead.org Cc: Philipp Rudo , Donald Dutile , Pingfan Liu , Tao Liu , linux-kernel@vger.kernel.org, David Hildenbrand , Michal Hocko Subject: [PATCH v4 3/5] kdump, documentation: describe craskernel CMA reservation Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Spam-Flag: NO X-Spam-Score: -4.30 X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.999]; MIME_GOOD(-0.10)[text/plain]; RCVD_COUNT_ZERO(0.00)[0]; ARC_NA(0.00)[]; MISSING_XM_UA(0.00)[]; RCPT_COUNT_SEVEN(0.00)[11]; MID_RHS_MATCH_FROMTLD(0.00)[]; FROM_HAS_DN(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; TO_DN_SOME(0.00)[] X-Spam-Level: Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Describe the new crashkernel ",cma" suffix in Documentation/ Signed-off-by: Jiri Bohac --- Documentation/admin-guide/kdump/kdump.rst | 21 ++++++++++++++++++ .../admin-guide/kernel-parameters.txt | 22 +++++++++++++++++++ 2 files changed, 43 insertions(+) diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admi= n-guide/kdump/kdump.rst index 1f7f14c6e184..089665731509 100644 --- a/Documentation/admin-guide/kdump/kdump.rst +++ b/Documentation/admin-guide/kdump/kdump.rst @@ -311,6 +311,27 @@ crashkernel syntax =20 crashkernel=3D0,low =20 +4) crashkernel=3Dsize,cma + + Reserve additional crash kernel memory from CMA. This reservation is + usable by the first system's userspace memory and kernel movable + allocations (memory balloon, zswap). Pages allocated from this memory + range will not be included in the vmcore so this should not be used if + dumping of userspace memory is intended and it has to be expected that + some movable kernel pages may be missing from the dump. + + A standard crashkernel reservation, as described above, is still needed + to hold the crash kernel and initrd. + + This option increases the risk of a kdump failure: DMA transfers + configured by the first kernel may end up corrupting the second + kernel's memory. + + This reservation method is intended for systems that can't afford to + sacrifice enough memory for standard crashkernel reservation and where + less reliable and possibly incomplete kdump is preferable to no kdump at + all. + Boot into System Kernel ----------------------- 1) Update the boot loader (such as grub, yaboot, or lilo) configuration diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index ea81784be981..ee6be52dd8a5 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -983,6 +983,28 @@ 0: to disable low allocation. It will be ignored when crashkernel=3DX,high is not used or memory reserved is below 4G. + crashkernel=3Dsize[KMG],cma + [KNL, X86] Reserve additional crash kernel memory from + CMA. This reservation is usable by the first system's + userspace memory and kernel movable allocations (memory + balloon, zswap). Pages allocated from this memory range + will not be included in the vmcore so this should not + be used if dumping of userspace memory is intended and + it has to be expected that some movable kernel pages + may be missing from the dump. + + A standard crashkernel reservation, as described above, + is still needed to hold the crash kernel and initrd. + + This option increases the risk of a kdump failure: DMA + transfers configured by the first kernel may end up + corrupting the second kernel's memory. + + This reservation method is intended for systems that + can't afford to sacrifice enough memory for standard + crashkernel reservation and where less reliable and + possibly incomplete kdump is preferable to no kdump at + all. =20 cryptomgr.notests [KNL] Disable crypto self-tests --=20 Jiri Bohac SUSE Labs, Prague, Czechia