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Re: [Minios-devel] [PATCH v3 20/43] mini-os: implement the memmove/memchr
- To: Huang Shijie <shijie.huang@xxxxxxx>
- From: Julien Grall <julien.grall@xxxxxxx>
- Date: Thu, 26 Apr 2018 10:03:58 +0100
- Cc: jgross@xxxxxxxx, wei.liu2@xxxxxxxxxx, wei.chen@xxxxxxx, steve.capper@xxxxxxx, vlad.babchuk@xxxxxxxxx, minios-devel@xxxxxxxxxxxxxxxxxxxx, kaly.xin@xxxxxxx, samuel.thibault@xxxxxxxxxxxx, baozich@xxxxxxxxx, nd@xxxxxxx
- Delivery-date: Thu, 26 Apr 2018 09:04:06 +0000
- List-id: Mini-os development list <minios-devel.lists.xenproject.org>
On 26/04/18 09:59, Huang Shijie wrote:
On Thu, Apr 26, 2018 at 09:49:20AM +0100, Julien Grall wrote:
On 26/04/18 09:42, Huang Shijie wrote:
On Wed, Apr 25, 2018 at 11:09:43AM +0100, Julien Grall wrote:
On 25/04/18 10:37, Huang Shijie wrote:
On Wed, Apr 25, 2018 at 10:10:58AM +0100, Julien Grall wrote:
On 04/16/2018 07:32 AM, Huang Shijie wrote:
This patch is split from the Chen Baozi's old patch:
"This activates the ARM code added in the previous patches. On
ARM, Mini-OS will boot and display some output on the console. Tested with:"
Note: The code is copied from FreeBSD code:
freebsd/contrib/ldns/compat/memmove.c
That's only for memmove. How about memchr?
The memchr is also from the FreeBSD code...
You specify the file for memmove.c. But not memchr.
Also, this seems to come from a userspace application and not the kernel.
Why not importing the assembly version (memmove.S and memcpy.S) that has
been optimized for aarch64?
okay. I can use the assembly version..
I was asking the rationale behind using userspace application memcpy over
the assembly one.
I did not check the rationale behind.
It works, then I used it.
I prefer to the C version which maybe used by x86. The assembly version is only
for arm64...
Well if there are an assembly version, then most likely there are a
reason behind :).
If you look around most of the time there will be a generic version
implemented in C and each architecture can override it for there own
version. This is how it is done in glibc, Linux, Xen, FreeBSD...
Anyway, that's not overly critical it seems to be only used at boot time.
Cheers,
--
Julien Grall
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