Hello, On 07/05/2019 04:50, Chen Zhou wrote: > In preparation for supporting reserving crashkernel above 4G > in arm64 as x86_64 does, move reserve_crashkernel_low() into > kexec/kexec_core.c.
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index 905dae8..9ee33b6 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -463,59 +460,6 @@ static void __init > memblock_x86_reserve_range_setup_data(void) > # define CRASH_ADDR_HIGH_MAX MAXMEM > #endif > > -static int __init reserve_crashkernel_low(void) > -{ > -#ifdef CONFIG_X86_64 The behaviour of this #ifdef has disappeared, won't 32bit x86 now try and reserve a chunk of unnecessary 'low' memory? [...] > @@ -579,9 +523,13 @@ static void __init reserve_crashkernel(void) > return; > } > > - if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) { > - memblock_free(crash_base, crash_size); > - return; > + if (crash_base >= (1ULL << 32)) { > + if (reserve_crashkernel_low()) { > + memblock_free(crash_base, crash_size); > + return; > + } > + > + insert_resource(&iomem_resource, &crashk_low_res); Previously reserve_crashkernel_low() was #ifdefed to do nothing if !CONFIG_X86_64, I don't see how 32bit is skipping this reservation... > } > > pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System > RAM: %ldMB)\n", > diff --git a/include/linux/kexec.h b/include/linux/kexec.h > index b9b1bc5..096ad63 100644 > --- a/include/linux/kexec.h > +++ b/include/linux/kexec.h > @@ -63,6 +63,10 @@ > > #define KEXEC_CORE_NOTE_NAME CRASH_CORE_NOTE_NAME > > +#ifndef CRASH_ALIGN > +#define CRASH_ALIGN SZ_128M > +#endif Why 128M? Wouldn't we rather each architecture tells us its minimum alignment? > diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c > index d714044..3492abd 100644 > --- a/kernel/kexec_core.c > +++ b/kernel/kexec_core.c > @@ -39,6 +39,8 @@ > #include <linux/compiler.h> > #include <linux/hugetlb.h> > #include <linux/frame.h> > +#include <linux/memblock.h> > +#include <linux/swiotlb.h> > > #include <asm/page.h> > #include <asm/sections.h> > @@ -96,6 +98,60 @@ int kexec_crash_loaded(void) > } > EXPORT_SYMBOL_GPL(kexec_crash_loaded); > > +int __init reserve_crashkernel_low(void) > +{ > + unsigned long long base, low_base = 0, low_size = 0; > + unsigned long total_low_mem; > + int ret; > + > + total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT)); > + > + /* crashkernel=Y,low */ > + ret = parse_crashkernel_low(boot_command_line, total_low_mem, > + &low_size, &base); > + if (ret) { > + /* > + * two parts from lib/swiotlb.c: > + * -swiotlb size: user-specified with swiotlb= or default. > + * > + * -swiotlb overflow buffer: now hardcoded to 32k. We round it > + * to 8M for other buffers that may need to stay low too. Also > + * make sure we allocate enough extra low memory so that we > + * don't run out of DMA buffers for 32-bit devices. > + */ > + low_size = max(swiotlb_size_or_default() + (8UL << 20), SZ_8M? > + 256UL << 20); SZ_256M? > + } else { > + /* passed with crashkernel=0,low ? */ > + if (!low_size) > + return 0; > + } > + > + low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN); > + if (!low_base) { > + pr_err("Cannot reserve %ldMB crashkernel low memory, please try > smaller size.\n", > + (unsigned long)(low_size >> 20)); > + return -ENOMEM; > + } > + > + ret = memblock_reserve(low_base, low_size); > + if (ret) { > + pr_err("%s: Error reserving crashkernel low memblock.\n", > + __func__); > + return ret; > + } > + > + pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System > low RAM: %ldMB)\n", > + (unsigned long)(low_size >> 20), > + (unsigned long)(low_base >> 20), > + (unsigned long)(total_low_mem >> 20)); > + > + crashk_low_res.start = low_base; > + crashk_low_res.end = low_base + low_size - 1; > + > + return 0; > +} Thanks, James