From: Richard Henderson <richard.henderson@linaro.org>
To: Warner Losh <imp@bsdimp.com>
Cc: qemu-devel@nongnu.org, "Thomas Huth" <thuth@redhat.com>,
"Kyle Evans" <kevans@freebsd.org>,
f4bug@amsat.org, "Alex Bennée" <alex.bennee@linaro.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Juergen Lock" <nox@jelal.kn-bremen.de>,
"Stacey Son" <sson@freebsd.org>
Subject: Re: [PATCH 6/9] bsd-user: common routine do_freebsd_sysctl_oid for all sysctl variants
Date: Sat, 11 Feb 2023 15:13:10 -1000 [thread overview]
Message-ID: <e4eeb2fc-d777-e7a8-17e8-38bd0104bf70@linaro.org> (raw)
In-Reply-To: <CANCZdfr=fFU8w6wEPWR77qTCAXe+a+HMj-Ubnsv=04Y3+qDX+Q@mail.gmail.com>
On 2/11/23 14:40, Warner Losh wrote:
> I was going to do something like:
>
> + if (host_page_size != TARGET_PAGE_SIZE) {
> + if (host_page_size > TARGET_PAGE_SIZE) {
> + /* Scale up */
> + pages *= host_page_size / TARGET_PAGE_SIZE;
> + } else {
> + /* Scale down with truncation */
> + pages /= TARGET_PAGE_SIZE / host_page_size;
> + }
> + }
> in a helper function. Does multdiv64 replace that?
Yes, it uses a 128-bit intermediate result, so no overflow.
Obviously the above works as well, but perhaps premature optimization.
r~
next prev parent reply other threads:[~2023-02-12 1:14 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-10 23:18 [PATCH 0/9] 2023 Q1 bsd-user upstreaming: bugfixes and sysctl Warner Losh
2023-02-10 23:18 ` [PATCH 1/9] bsd-user: Don't truncate the return value from freebsd_syscall Warner Losh
2023-02-11 19:12 ` Richard Henderson
2023-02-10 23:18 ` [PATCH 2/9] build: Don't specify -no-pie for --static user-mode programs Warner Losh
2023-02-10 23:18 ` [PATCH 3/9] bsd-user: Add sysarch syscall Warner Losh
2023-02-11 19:27 ` Richard Henderson
2023-02-10 23:18 ` [PATCH 4/9] bsd-user: Two helper routines oidfmt and sysctl_oldcvt Warner Losh
2023-02-11 22:17 ` Richard Henderson
2023-02-12 4:11 ` Warner Losh
2023-02-12 17:01 ` Warner Losh
2023-02-12 17:11 ` Warner Losh
2023-02-10 23:18 ` [PATCH 5/9] bsd-user: sysctl helper funtions: sysctl_name2oid and sysctl_oidfmt Warner Losh
2023-02-10 23:18 ` [PATCH 6/9] bsd-user: common routine do_freebsd_sysctl_oid for all sysctl variants Warner Losh
2023-02-11 22:56 ` Richard Henderson
2023-02-11 23:40 ` Warner Losh
2023-02-11 23:59 ` Richard Henderson
2023-02-12 0:40 ` Warner Losh
2023-02-12 1:13 ` Richard Henderson [this message]
2023-02-10 23:18 ` [PATCH 7/9] bsd-user: do_freebsd_sysctl helper for sysctl(2) Warner Losh
2023-02-11 23:09 ` Richard Henderson
2023-02-12 17:53 ` Warner Losh
2023-02-10 23:18 ` [PATCH 8/9] bsd-user: implement sysctlbyname(2) Warner Losh
2023-02-11 23:13 ` Richard Henderson
2023-02-12 4:23 ` Kyle Evans
2023-02-12 15:07 ` Richard Henderson
2023-02-10 23:18 ` [PATCH 9/9] bsd-user: Add -strict Warner Losh
2023-02-11 23:19 ` Richard Henderson
2023-02-13 23:55 ` Warner Losh
2023-02-11 19:30 ` [PATCH 0/9] 2023 Q1 bsd-user upstreaming: bugfixes and sysctl Richard Henderson
2023-02-11 22:20 ` Warner Losh
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