Re: [PATCH] x86: Remove excess calculations for heap_end_ptr
From: H. Peter Anvin
Date: Fri Dec 26 2014 - 12:05:14 EST
Yes, the -512 is not related to STACK_SIZE, so this patch is wrong. NAK.
On December 26, 2014 9:03:38 AM PST, Alexander Kuleshov <kuleshovmail@xxxxxxxxx> wrote:
>Yes, you're right,
>At first i thought that it is just typo, and right after that i
>thought about this case when somebody will change STACK_SIZE
>2014-12-26 20:35 GMT+06:00 Jeremiah Mahler <jmmahler@xxxxxxxxx>:
>> On Fri, Dec 26, 2014 at 06:22:42PM +0600, Alexander Kuleshov wrote:
>>> heap_end_ptr default value defined as _end+STACK_SZE-512, but
>>> STACK_SIZE is already 512.
>>> Signed-off-by: Alexander Kuleshov <kuleshovmail@xxxxxxxxx>
>>> arch/x86/boot/header.S | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>> diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
>>> index 16ef025..c69b870 100644
>>> --- a/arch/x86/boot/header.S
>>> +++ b/arch/x86/boot/header.S
>>> @@ -342,7 +342,7 @@ ramdisk_size: .long 0 # its
>size in bytes
>>> .long 0 # obsolete
>>> -heap_end_ptr: .word _end+STACK_SIZE-512
>>> +heap_end_ptr: .word _end
>>> # (Header version 0x0201 or
>>> # space from here (exclusive)
>>> # end of setup code can be
>used by setup
>> So right now STACK_SIZE happens to be 512 so STACK_SIZE-512 is zero.
>> What happens if someone changes the size of STACK_SIZE?
>> This change doesn't fix any problem right now and creates potential
>> problems in the future.
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>> - Jeremiah Mahler
Sent from my mobile phone. Please pardon brevity and lack of formatting.
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