From: "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
To: Yinghai Lu <yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: "Matt Fleming"
<matt.fleming-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
"Ingo Molnar" <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
"Mantas Mikulėnas"
<grawity-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
"Anders Darander"
<anders-7UjN0b3lYz2SbKU13Z4Etw@public.gmane.org>,
linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
"Linux Kernel Mailing List"
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH] x86: only load initrd above 4g on second try
Date: Wed, 27 Aug 2014 10:49:31 -0700 [thread overview]
Message-ID: <53FE1A2B.80204@zytor.com> (raw)
In-Reply-To: <CAE9FiQUF4THLRfzbnhK61QHpM2zyox4E8LTmyzVF7PnPdpb7jQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On 08/26/2014 03:05 PM, Yinghai Lu wrote:
>
> The firmware has bug and can use buffer above 4G to read files.
> and if the file size is 512 bytes alignment, then reading could go through.
>
File size, or alignment? Different things. Again, your patch
description is not just incomplete, but seems to be actively misleading.
This does, however, suggest at least two possible solutions:
1. We can read the initramfs into a temporary buffer and memcpy() it to
the target.
2. We might be able to align the initramfs buffer to a 512-byte section
and then round up the size.
The 512 bytes here is probably a hardware sector, I'm not sure how this
will play on 4K-hard-sectored media, although those are few and far between.
-hpa
WARNING: multiple messages have this Message-ID (diff)
From: "H. Peter Anvin" <hpa@zytor.com>
To: Yinghai Lu <yinghai@kernel.org>
Cc: "Matt Fleming" <matt.fleming@intel.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Mantas Mikulėnas" <grawity@gmail.com>,
"Anders Darander" <anders@chargestorm.se>,
linux-efi@vger.kernel.org,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86: only load initrd above 4g on second try
Date: Wed, 27 Aug 2014 10:49:31 -0700 [thread overview]
Message-ID: <53FE1A2B.80204@zytor.com> (raw)
In-Reply-To: <CAE9FiQUF4THLRfzbnhK61QHpM2zyox4E8LTmyzVF7PnPdpb7jQ@mail.gmail.com>
On 08/26/2014 03:05 PM, Yinghai Lu wrote:
>
> The firmware has bug and can use buffer above 4G to read files.
> and if the file size is 512 bytes alignment, then reading could go through.
>
File size, or alignment? Different things. Again, your patch
description is not just incomplete, but seems to be actively misleading.
This does, however, suggest at least two possible solutions:
1. We can read the initramfs into a temporary buffer and memcpy() it to
the target.
2. We might be able to align the initramfs buffer to a 512-byte section
and then round up the size.
The 512 bytes here is probably a hardware sector, I'm not sure how this
will play on 4K-hard-sectored media, although those are few and far between.
-hpa
next prev parent reply other threads:[~2014-08-27 17:49 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-26 21:45 [PATCH] x86: only load initrd above 4g on second try Yinghai Lu
2014-08-26 21:45 ` Yinghai Lu
[not found] ` <1409089544-24221-1-git-send-email-yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2014-08-26 21:53 ` H. Peter Anvin
2014-08-26 21:53 ` H. Peter Anvin
[not found] ` <53FD01D0.8020203-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
2014-08-26 22:05 ` Yinghai Lu
2014-08-26 22:05 ` Yinghai Lu
[not found] ` <CAE9FiQUF4THLRfzbnhK61QHpM2zyox4E8LTmyzVF7PnPdpb7jQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-08-26 22:16 ` Mantas Mikulėnas
2014-08-26 22:16 ` Mantas Mikulėnas
[not found] ` <CAPWNY8WG3E7oZdZDdYsrnGM5pG4kWAKkEq0Eh5Hc_uXJ_8zD5g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-08-26 22:58 ` Yinghai Lu
2014-08-26 22:58 ` Yinghai Lu
2014-08-27 17:49 ` H. Peter Anvin [this message]
2014-08-27 17:49 ` H. Peter Anvin
[not found] ` <53FE1A2B.80204-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
2014-08-27 18:50 ` Yinghai Lu
2014-08-27 18:50 ` Yinghai Lu
2014-08-27 10:59 ` Matt Fleming
2014-08-27 10:59 ` Matt Fleming
[not found] ` <20140827105901.GC28116-HNK1S37rvNbeXh+fF434Mdi2O/JbrIOy@public.gmane.org>
2014-08-27 17:13 ` Yinghai Lu
2014-08-27 17:13 ` Yinghai Lu
[not found] ` <CAE9FiQWrPtEe3tkJjgOzyJJPPzX=AtMYgR4c91pDHL3q3ZLLKQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-08-30 11:24 ` Matt Fleming
2014-08-30 11:24 ` Matt Fleming
[not found] ` <20140830112426.GA2911-HNK1S37rvNbeXh+fF434Mdi2O/JbrIOy@public.gmane.org>
2014-09-02 6:57 ` Anders Darander
2014-09-02 6:57 ` Anders Darander
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