On Thu, 25 Sept 2025 at 17:26, Youling Tang <[email protected]> wrote: > > Hi, Dave > > On 9/25/25 17:11, Dave Young wrote: > > Hi Youling, > > > > On Thu, 25 Sept 2025 at 14:33, Youling Tang <[email protected]> wrote: > >> From: Youling Tang <[email protected]> > >> > >> During kdump operations, the capture kernel cannot reuse the "mem=" > >> parameter from the production kernel. The "mem=" parameter is used > >> to specify the available memory range for the kernel. Reusing the > >> "mem=" memory range may destroy the production environment. > >> > >> Signed-off-by: Youling Tang <[email protected]> > >> --- > >> kexec/kexec.c | 4 +++- > >> 1 file changed, 3 insertions(+), 1 deletion(-) > >> > >> diff --git a/kexec/kexec.c b/kexec/kexec.c > >> index c9e4bcb..fadf986 100644 > >> --- a/kexec/kexec.c > >> +++ b/kexec/kexec.c > >> @@ -1256,8 +1256,10 @@ char *get_command_line(void) > >> *p = '\0'; > >> > >> remove_parameter(line, "BOOT_IMAGE"); > >> - if (kexec_flags & KEXEC_ON_CRASH) > >> + if (kexec_flags & KEXEC_ON_CRASH) { > >> remove_parameter(line, "crashkernel"); > >> + remove_parameter(line, "mem="); > >> + } > > People can remove it from the kdump load scripts instead if it is not > > useful. I do not suggest removing other cmdline in c code. The > > crashkernel is a special one which is fine. > Removing it in scripts is also acceptable. However, reusing the > production kernel's > "mem=" parameter will inevitably damage the production environment. In > my view, > modifying it in C code can achieve a permanent solution (avoiding the > need to > modify kdump services for each distribution, and also applicable to > non-kdump > services scenarios where commands are executed directly).
But the param is a general one, not specific for kexec, people can use it in their own way, eg. use less memory to boot a machine for debug purposes. This is why I suggest doing it in scripts and distributions. The two kdump related param, crashkernel and elfcorehdr are special anyway. > > Thanks, > Youling. > >> return line; > >> } > >> -- > >> 2.48.1 > >> > >> > > Thanks > > Dave > > >
