On Tue, Oct 06, 2020 at 10:10:54AM +0800, chenzhou wrote: > On 2020/10/6 1:19, Catalin Marinas wrote: > > 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. > How about like this: > If the kernel config ZONE_DMA is disabled, just try low allocation in DMA32 zone > and high allocation above DMA32 zone. Something like: "allocate 256M low memory in the DMA zone automatically (or the DMA32 zone if CONFIG_ZONE_DMA is disabled)". I'd keep it short. -- Catalin _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
