Hi Dave, On 2020/7/2 10:59, Dave Young wrote: > Hi Chen, > On 06/28/20 at 04:34pm, Chen Zhou wrote: >> Now we support crashkernel=X,[low] on arm64, update the Documentation. >> We could use parameters "crashkernel=X crashkernel=Y,low" to reserve >> memory above 4G. >> >> Signed-off-by: Chen Zhou <chenzhou10@xxxxxxxxxx> >> Tested-by: John Donnelly <John.p.donnelly@xxxxxxxxxx> >> Tested-by: Prabhakar Kushwaha <pkushwaha@xxxxxxxxxxx> >> --- >> Documentation/admin-guide/kdump/kdump.rst | 13 +++++++++++-- >> Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++-- >> 2 files changed, 26 insertions(+), 4 deletions(-) >> >> diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst >> index 2da65fef2a1c..6ba294d425c9 100644 >> --- a/Documentation/admin-guide/kdump/kdump.rst >> +++ b/Documentation/admin-guide/kdump/kdump.rst >> @@ -299,7 +299,13 @@ Boot into System Kernel >> "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory >> starting at physical address 0x01000000 (16MB) for the dump-capture kernel. >> >> - On x86 and x86_64, use "crashkernel=64M@16M". >> + On x86 use "crashkernel=64M@16M". >> + >> + On x86_64, use "crashkernel=Y[@X]" to select a region under 4G first, and >> + fall back to reserve region above 4G when '@offset' hasn't been specified. > Actually crashkernel=Y without the offset works well, I do not see why > we need the offset, it should be some legacy thing. So it should be > better just use the Y without offset here, and just leave a note > somewhere people can use [@X] offset when they really have to. > >> + We can also use "crashkernel=X,high" to select a region above 4G, which >> + also tries to allocate at least 256M below 4G automatically and >> + "crashkernel=Y,low" can be used to allocate specified size low memory. >> >> On ppc64, use "crashkernel=128M@32M". >> >> @@ -316,8 +322,11 @@ 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 >> + On arm64, use "crashkernel=Y[@X]". Note that the start address of >> the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000). >> + If crashkernel=Z,low is specified simultaneously, reserve spcified size >> + low memory for crash kdump kernel devices firstly and then reserve memory > "devices" seems not very accurate, maybe just drop the "for crash kdump > kernel devices" since it is clear based on the context. > >> + above 4G. >> >> Load the Dump-capture Kernel >> ============================ >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >> index fb95fad81c79..335431a351c0 100644 >> --- a/Documentation/admin-guide/kernel-parameters.txt >> +++ b/Documentation/admin-guide/kernel-parameters.txt >> @@ -722,6 +722,9 @@ >> [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] If crashkernel=X,low is specified, reserve >> + spcified size low memory for crash kdump kernel devices > Ditto. > >> + firstly, and then reserve memory above 4G. >> See Documentation/admin-guide/kdump/kdump.rst for further details. >> >> crashkernel=range1:size1[,range2:size2,...][@offset] >> @@ -746,13 +749,23 @@ >> 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 under 4G. >> + This one let user to specify own low range under 4G >> + for crash dump kernel instead. >> + Different with x86_64, kernel allocates specified size > sounds better: > s/Different with/Be different from > > s/allocates/reserves > >> + physical memory region only when this parameter is specified >> + instead of trying to allocate at least 256M below 4G > s/allocate/reserve > >> + automatically. >> + This parameter is used along with crashkernel=X when we > Could change the passive sentence to below: > "Use this parameter along with" Thanks for your review and suggestions. I will update these in next version. Thanks, Chen Zhou >> + want to reserve crashkernel above 4G. If there are devices >> + need to use ZONE_DMA in crash dump kernel, it is also >> + a good choice. >> cryptomgr.notests >> [KNL] Disable crypto self-tests >> >> -- >> 2.20.1 >> >> >> _______________________________________________ >> kexec mailing list >> kexec@xxxxxxxxxxxxxxxxxxx >> http://lists.infradead.org/mailman/listinfo/kexec >> > Thanks > Dave > > > . >
