On 2022/2/21 11:48, Baoquan He wrote: > 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. I agree very much, and I think that's the right thing to do. Thanks. I wanted to do the same before, just wasn't sure if the format was correct. I just looked at the other descriptions in kernel-parameters.txt and found that there are many precedents. "movablecore= [KNL,X86,IA-64,PPC]" > >> >> 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 >> > > . > -- Regards, Zhen Lei
