From: "Maciej W. Rozycki" <macro@linux-mips.org>
To: Fredrik Noring <noring@nocrew.org>
Cc: "Aleksandar Markovic" <amarkovic@wavecomp.com>,
"Philippe Mathieu-Daudé" <f4bug@amsat.org>,
"Richard Henderson" <richard.henderson@linaro.org>,
"Aurelien Jarno" <aurelien@aurel32.net>,
"qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>,
"Jürgen Urban" <JuergenUrban@gmx.de>
Subject: Re: [Qemu-devel] [PATCH] target/mips: Support Toshiba specific three-operand MADD and MADDU
Date: Tue, 16 Oct 2018 19:55:45 +0100 (BST) [thread overview]
Message-ID: <alpine.LFD.2.21.1810161947360.16498@eddie.linux-mips.org> (raw)
In-Reply-To: <20181016181916.GB2323@sx9>
On Tue, 16 Oct 2018, Fredrik Noring wrote:
> One option is to create a new array such as
>
> static TCGv_i64 mmi_gpr[32];
>
> that represents the upper 64 bits of each GPR. Then cpu_gpr must be of
> a 64-bit type too, even when QEMU runs in 32-bit user mode. The R5900
> does not implement CP0.Status.UX in hardware, though, so system mode is
> 64 bits, regardless.
It's more like modern CP0.Status.PX however, as the hardware does not
implement 64-bit memory segments and only has legacy 32-bit segments
implemented.
Due to a hardware quirk however the value recorded in the target register
(usually $ra) does not get sign-extended with linked jump or branch
instructions, contrary to what is expected with processors implementing
32-bit segments only. This has implications for kernel code running from
KSEG0/KSEG1/KSEG2 and has to be worked around in software, as experience
has shown.
Maciej
next prev parent reply other threads:[~2018-10-16 18:55 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-14 14:29 [Qemu-devel] [PATCH] target/mips: Support Toshiba specific three-operand MADD and MADDU Philippe Mathieu-Daudé
2018-10-14 16:41 ` Fredrik Noring
2018-10-14 21:56 ` Philippe Mathieu-Daudé
2018-10-14 23:03 ` Maciej W. Rozycki
2018-10-15 17:02 ` Fredrik Noring
2018-10-16 9:43 ` Aleksandar Markovic
2018-10-16 18:19 ` Fredrik Noring
2018-10-16 18:37 ` Richard Henderson
2018-10-16 18:52 ` Fredrik Noring
2018-10-16 19:02 ` Maciej W. Rozycki
2018-10-19 18:09 ` Aleksandar Markovic
2018-10-28 19:43 ` Aleksandar Markovic
2018-10-28 20:00 ` Maciej W. Rozycki
2018-10-29 11:52 ` Aleksandar Markovic
2018-10-29 14:51 ` Fredrik Noring
2018-10-29 15:03 ` Aleksandar Markovic
2018-10-29 15:44 ` Maciej W. Rozycki
2018-10-16 18:55 ` Maciej W. Rozycki [this message]
2018-10-15 15:36 ` Fredrik Noring
2018-10-24 18:01 ` Fredrik Noring
2018-10-26 11:17 ` Aleksandar Markovic
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=alpine.LFD.2.21.1810161947360.16498@eddie.linux-mips.org \
--to=macro@linux-mips.org \
--cc=JuergenUrban@gmx.de \
--cc=amarkovic@wavecomp.com \
--cc=aurelien@aurel32.net \
--cc=f4bug@amsat.org \
--cc=noring@nocrew.org \
--cc=qemu-devel@nongnu.org \
--cc=richard.henderson@linaro.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.