On 01/24/22 at 04:47pm, Zhen Lei wrote: > From: Chen Zhou <chenzhou10@xxxxxxxxxx> > > For arm64, the behavior of crashkernel=X has been changed, which > tries low allocation in DMA zone and fall back to high allocation > if it fails. > > We can also use "crashkernel=X,high" to select a high region above > DMA zone, which also tries to allocate at least 256M low memory in > DMA zone automatically and "crashkernel=Y,low" can be used to allocate > specified size low memory. > > So update the Documentation. > > Signed-off-by: Chen Zhou <chenzhou10@xxxxxxxxxx> > Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx> > --- > Documentation/admin-guide/kdump/kdump.rst | 11 +++++++++-- > Documentation/admin-guide/kernel-parameters.txt | 11 +++++++++-- > 2 files changed, 18 insertions(+), 4 deletions(-) > > diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst > index cb30ca3df27c9b2..d4c287044be0c70 100644 > --- a/Documentation/admin-guide/kdump/kdump.rst > +++ b/Documentation/admin-guide/kdump/kdump.rst > @@ -361,8 +361,15 @@ Boot into System Kernel > kernel will automatically locate the crash kernel image within the > first 512MB of RAM if X is not given. > > - On arm64, use "crashkernel=Y[@X]". Note that the start address of > - the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000). > + On arm64, use "crashkernel=X" to try low allocation in DMA zone and > + fall back to high allocation if it fails. > + We can also use "crashkernel=X,high" to select a high region above > + DMA zone, which also tries to allocate at least 256M low memory in > + DMA zone automatically. > + "crashkernel=Y,low" can be used to allocate specified size low memory. > + Use "crashkernel=Y@X" if you really have to reserve memory from > + specified start address X. Note that the start address of the kernel, > + X if explicitly specified, must be aligned to 2MiB (0x200000). Hmm, we may not need the details related to crashkernel,high|low in this section. This just gives examples of basic configation for each ARCH. The detailed configuration of all crashkernel setting can be found in "crashkernel syntax" section, I don't think arm64 is so special to need a specific one. > > Load the Dump-capture Kernel > ============================ > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index f5a27f067db9ed9..65780c2ca830be0 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -792,6 +792,9 @@ > [KNL, X86-64] Select a region under 4G first, and > fall back to reserve region above 4G when '@offset' > hasn't been specified. > + [KNL, ARM64] Try low allocation in DMA zone and fall back > + to high allocation if it fails when '@offset' hasn't been > + specified. > See Documentation/admin-guide/kdump/kdump.rst for further details. How about add ARM64 like below to avoid redundant words? [KNL, X86-64, ARM64] Select a region under 4G first, and fall back to reserve region above 4G when '@offset' hasn't been specified. > > crashkernel=range1:size1[,range2:size2,...][@offset] > @@ -808,6 +811,8 @@ > Otherwise memory region will be allocated below 4G, if > available. > It will be ignored if crashkernel=X is specified. > + [KNL, ARM64] range in high memory. > + Allow kernel to allocate physical memory region from top. Ditto, please don't add redundent words if it's similar to x86_64 handling. > crashkernel=size[KMG],low > [KNL, X86-64] range under 4G. When crashkernel=X,high > is passed, kernel could allocate physical memory region > @@ -816,13 +821,15 @@ > requires at least 64M+32K low memory, also enough extra > low memory is needed to make sure DMA buffers for 32-bit > devices won't run out. Kernel would try to allocate at > - at least 256M below 4G automatically. > + least 256M below 4G automatically. > This one let user to specify own low range under 4G > for second kernel instead. > 0: to disable low allocation. > It will be ignored when crashkernel=X,high is not used > or memory reserved is below 4G. > - > + [KNL, ARM64] range in low memory. > + This one let user to specify a low range in DMA zone for > + crash dump kernel. Ditto. > cryptomgr.notests > [KNL] Disable crypto self-tests > > -- > 2.25.1 >
