On Mon, Sep 07, 2020 at 09:47:45PM +0800, Chen Zhou wrote: > diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst > index 2da65fef2a1c..549611abc581 100644 > --- a/Documentation/admin-guide/kdump/kdump.rst > +++ b/Documentation/admin-guide/kdump/kdump.rst [...] > @@ -316,8 +325,18 @@ 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. And go for high allocation > + directly if the required size is too large. > + 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 > + in DMA zone. > + For non-RPi4 platforms, change DMA zone memtioned above to DMA32 zone. I don't think we should mention non-RPi4 explicitly here. I don't even understand what the suggestion is since the only way is to disable ZONE_DMA in the kernel config. I'd just stick to ZONE_DMA description here. > + 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). > > Load the Dump-capture Kernel > ============================ > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index a1068742a6df..f7df572d8f64 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -727,6 +727,10 @@ > [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, fall back > + to high allocation if it fails when '@offset' hasn't been > + specified. For non-RPi4 platforms, change DMA zone to > + DMA32 zone. Same here, unclear what "change DMA zone to DMA32 zone" means. > See Documentation/admin-guide/kdump/kdump.rst for further details. > > crashkernel=range1:size1[,range2:size2,...][@offset] > @@ -743,6 +747,8 @@ > 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. > crashkernel=size[KMG],low > [KNL, X86-64] range under 4G. When crashkernel=X,high > is passed, kernel could allocate physical memory region > @@ -751,13 +757,16 @@ > 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. For non-RPi4 platforms, change DMA zone > + to DMA32 zone. And again here. -- Catalin _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
