From: Xi Ruoyao <xry111@xry111.site>
To: Sui Jingfeng <suijingfeng@loongson.cn>,
WANG Xuerui <kernel@xen0n.name>, Icenowy Zheng <uwu@icenowy.me>,
Huacai Chen <chenhuacai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Weihao Li <liweihao@loongson.cn>,
"Mike Rapoport (IBM)" <rppt@kernel.org>,
Jun Yi <yijun@loongson.cn>, Baoquan He <bhe@redhat.com>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
David Hildenbrand <david@redhat.com>,
Hongchen Zhang <zhanghongchen@loongson.cn>,
Binbin Zhou <zhoubinbin@loongson.cn>,
Zhen Lei <thunder.leizhen@huawei.com>,
Tiezhu Yang <yangtiezhu@loongson.cn>,
Thomas Gleixner <tglx@linutronix.de>,
Zhihong Dong <donmor3000@hotmail.com>,
loongarch@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] loongarch/mm: disable WUC for pgprot_writecombine as same as ioremap_wc
Date: Fri, 13 Oct 2023 21:53:21 +0800 [thread overview]
Message-ID: <00d5150cadcb8b60004284ad43810adef52aab37.camel@xry111.site> (raw)
In-Reply-To: <049fbd3906b60f75be3900f20f6974967da374f3.camel@xry111.site>
On Fri, 2023-10-13 at 21:15 +0800, Xi Ruoyao wrote:
> Again, why this is only an issue with AMD or ATI GPUs?
>
> Can you provide some detailed documentations about this hardware issue
> so the community can help to figure out a solution?
3 years ago we had https://lkml.org/lkml/2020/8/10/255:
In this case the patch is a clear NAK since you haven't root caused the
issue and are just working around it in a very questionable manner.
and
But when the hardware doesn't correctly implement WC for PCIe BARs, then
this is a violation of the PCIe spec and a bit more serious issue for
the whole platform.
So do we know the root cause now? <rant>Or in all the 3 years we just
keep carrying a problematic workaround downstream, burying the head into
the sand like an ostrich, and self comforting with "oh they don't
understand our hardware"?!</rant>
Even if the problem is really "they don't understand our hardware" you
need to provide some materials to help people understanding the hardware
better.
If we cannot figure out the root cause or a proper fix is too difficult,
we should *at least* have a cmdline option and/or a configuration option
to allow the user to decide, like how we treat these spectre-like bugs.
"Should the option be enabled or disabled by default" can be debated
later.
And please try to fix the hardware, to me it will be a compelling reason
to pay some money for an upgrade :).
--
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University
next prev parent reply other threads:[~2023-10-13 13:53 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-09 4:28 [PATCH v2] loongarch/mm: disable WUC for pgprot_writecombine as same as ioremap_wc Icenowy Zheng
2023-10-09 14:32 ` Sui Jingfeng
2023-10-10 0:15 ` WANG Xuerui
2023-10-10 3:02 ` Sui Jingfeng
2023-10-10 12:26 ` Xi Ruoyao
2023-10-13 11:12 ` Sui Jingfeng
2023-10-13 12:51 ` Sui Jingfeng
2023-10-13 13:15 ` Xi Ruoyao
2023-10-13 13:53 ` Xi Ruoyao [this message]
2023-10-10 0:50 ` Icenowy Zheng
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=00d5150cadcb8b60004284ad43810adef52aab37.camel@xry111.site \
--to=xry111@xry111.site \
--cc=akpm@linux-foundation.org \
--cc=bhe@redhat.com \
--cc=chenhuacai@kernel.org \
--cc=david@redhat.com \
--cc=donmor3000@hotmail.com \
--cc=kernel@xen0n.name \
--cc=linux-kernel@vger.kernel.org \
--cc=liweihao@loongson.cn \
--cc=loongarch@lists.linux.dev \
--cc=rppt@kernel.org \
--cc=suijingfeng@loongson.cn \
--cc=tglx@linutronix.de \
--cc=thunder.leizhen@huawei.com \
--cc=uwu@icenowy.me \
--cc=willy@infradead.org \
--cc=yangtiezhu@loongson.cn \
--cc=yijun@loongson.cn \
--cc=zhanghongchen@loongson.cn \
--cc=zhoubinbin@loongson.cn \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).