Messages in this thread Patch in this message |  | | From | Ingo Molnar <> | Subject | [PATCH 20/50] x86/boot/e820: Rename memblock_x86_fill() to e820__memblock_setup() and improve the explanations | Date | Sat, 28 Jan 2017 23:11:41 +0100 |
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So memblock_x86_fill() is another E820 code misnomer:
- nothing in its name tells us that it's part of the E820 subsystem ...
- The 'fill' wording is ambiguous and doesn't tell us whether it's a single entry or some process - while the _real_ purpose of the function is hidden, which is to do a complete setup of the (platform independent) memblock regions.
So rename it accordingly, to e820__memblock_setup().
Also translate this incomprehensible and misleading comment:
/* * EFI may have more than 128 entries * We are safe to enable resizing, beause memblock_x86_fill() * is rather later for x86 */ memblock_allow_resize();
The worst aspect of this comment isn't even the sloppy typos, but that it casually mentions a '128' number with no explanation, which makes one lead to the assumption that this is related to the well-known limit of a maximum of 128 E820 entries passed via legacy bootloaders.
But no, the _real_ meaning of 128 here is that of the memblock subsystem, which too happens to have a 128 entries limit for very early memblock regions (which is unrelated to E820), via INIT_MEMBLOCK_REGIONS ...
So change the comment to a more comprehensible version:
/* * The bootstrap memblock region count maximum is 128 entries * (INIT_MEMBLOCK_REGIONS), but EFI might pass us more E820 entries * than that - so allow memblock resizing. * * This is safe, because this call happens pretty late during x86 setup, * so we know about reserved memory regions already. (This is important * so that memblock resizing does no stomp over reserved areas.) */ memblock_allow_resize();
No change in functionality.
Cc: Alex Thorlton <athorlton@sgi.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Huang, Ying <ying.huang@intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Jackson <pj@sgi.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> --- arch/x86/include/asm/e820/api.h | 2 +- arch/x86/kernel/e820.c | 14 +++++++++----- arch/x86/kernel/setup.c | 4 ++-- 3 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/e820/api.h b/arch/x86/include/asm/e820/api.h index 2c336d8a8593..01698548fbc8 100644 --- a/arch/x86/include/asm/e820/api.h +++ b/arch/x86/include/asm/e820/api.h @@ -21,7 +21,7 @@ extern void parse_e820_ext(u64 phys_addr, u32 data_len); extern unsigned long e820_end_of_ram_pfn(void); extern unsigned long e820_end_of_low_ram_pfn(void); extern u64 early_reserve_e820(u64 sizet, u64 align); -extern void memblock_x86_fill(void); +extern void e820__memblock_setup(void); extern void memblock_find_dma_reserve(void); extern void finish_e820_parsing(void); extern void e820_reserve_resources(void); diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index 624190fe86a7..b8e216b3957a 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -1138,15 +1138,19 @@ void __init e820__memory_setup(void) e820_print_map(who); } -void __init memblock_x86_fill(void) +void __init e820__memblock_setup(void) { int i; u64 end; /* - * EFI may have more than 128 entries - * We are safe to enable resizing, beause memblock_x86_fill() - * is rather later for x86 + * The bootstrap memblock region count maximum is 128 entries + * (INIT_MEMBLOCK_REGIONS), but EFI might pass us more E820 entries + * than that - so allow memblock resizing. + * + * This is safe, because this call happens pretty late during x86 setup, + * so we know about reserved memory regions already. (This is important + * so that memblock resizing does no stomp over reserved areas.) */ memblock_allow_resize(); @@ -1163,7 +1167,7 @@ void __init memblock_x86_fill(void) memblock_add(ei->addr, ei->size); } - /* throw away partial pages */ + /* Throw away partial pages: */ memblock_trim_memory(PAGE_SIZE); memblock_dump_all(); diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index f905430d7b04..838e4b5707ae 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1109,7 +1109,7 @@ void __init setup_arch(char **cmdline_p) early_alloc_pgt_buf(); /* - * Need to conclude brk, before memblock_x86_fill() + * Need to conclude brk, before e820__memblock_setup() * it could use memblock_find_in_range, could overlap with * brk area. */ @@ -1118,7 +1118,7 @@ void __init setup_arch(char **cmdline_p) cleanup_highmap(); memblock_set_current_limit(ISA_END_ADDRESS); - memblock_x86_fill(); + e820__memblock_setup(); reserve_bios_regions(); -- 2.7.4
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