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SubjectRe: [PATCH] x86/kexec: do not reserve kexec setup_data in kexec e820 table
On 02/12/20 at 07:04pm, Dave Young wrote:
> The e820 table for kexec kernel always takes setup_data as reserved.
> It is reasonable for the setup_data passed by the 1st kernel boot loader,
> for example SETUP_PCI etc. But SETUP_EFI is used by kexec itself to
> enable EFI in 2nd kernel, also kexec setups it every time. Thus it
> is pointless to reserve kexec prepared setup_data.
>
> 1st physical boot: no SETUP_EFI
> kexec load new kernel and prepare a SETUP_EFI setup_data, then reboot
> -> 2nd kernel sees SETUP_EFI, reserves in both e820 and kexec e820
> another kexec load prepare a new SETUP_EFI, then reboot
> -> 3rd kernel has two SETUP_EFI ranges reserved
> -> and so on..
>
> Thus skip SETUP_EFI while reserving setup_data for kexec kernel.
>
> Signed-off-by: Dave Young <dyoung@redhat.com>
> ---
> arch/x86/kernel/e820.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> --- linux-x86.orig/arch/x86/kernel/e820.c
> +++ linux-x86/arch/x86/kernel/e820.c
> @@ -999,7 +999,9 @@ void __init e820__reserve_setup_data(voi
> while (pa_data) {
> data = early_memremap(pa_data, sizeof(*data));
> e820__range_update(pa_data, sizeof(*data)+data->len, E820_TYPE_RAM, E820_TYPE_RESERVED_KERN);
> - e820__range_update_kexec(pa_data, sizeof(*data)+data->len, E820_TYPE_RAM, E820_TYPE_RESERVED_KERN);
> + /* Skip kexec passed setup_data */
> + if (data->type != SETUP_EFI)
> + e820__range_update_kexec(pa_data, sizeof(*data)+data->len, E820_TYPE_RAM, E820_TYPE_RESERVED_KERN);
>
> if (data->type == SETUP_INDIRECT &&
> ((struct setup_indirect *)data->data)->type != SETUP_INDIRECT) {

Ping, can someone review this? It caused fragmented memory in kexec
kernel also waste memory.

Thanks
Dave

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