linux-kernel - Re: [RFC][PATCH] tracing/x86: Save CR2 before tracing irqsoff on error

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Message-ID: <452B5054-91CC-48EE-A500-C251223B8F2D@zytor.com>
Date:   Thu, 21 Mar 2019 11:22:22 -0700
From:   hpa@...or.com
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Lutomirski <luto@...capital.net>
CC:     Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Juergen Gross <jgross@...e.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        Joel Fernandes <joel@...lfernandes.org>,
        He Zhe <zhe.he@...driver.com>
Subject: Re: [RFC][PATCH] tracing/x86: Save CR2 before tracing irqsoff on error_entry

On March 21, 2019 11:18:53 AM PDT, Linus Torvalds <torvalds@...ux-foundation.org> wrote:
>On Thu, Mar 21, 2019 at 11:05 AM Andy Lutomirski <luto@...capital.net>
>wrote:
>>
>> In the long run, I think the right solution is to rewrite even more
>of
>> this mess in C.  We really ought to be able to put the IRQ flag
>> tracing and the context tracking into C code.
>
>Tangentially about this long run thing - can we start discussing just
>dropping PV mode entirely in the long run? Or even not-so-long run?
>
>What are the pressing advantages of paravirt these days? Because I can
>point to a lot of pressing _disadvantages_, and not all of them are
>about more complex code as shown by this patch...
>
>             Linus

God only knows how nice that would be (for things that aren't naturally driverized.) Last I heard, which was quite a while ago, the big problem was that the Amazon cloud runs Xen in PV mode...
-- 
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