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Re: [Qemu-devel] [RFC] linux-user (mostly syscall.c)
From: |
Thiemo Seufer |
Subject: |
Re: [Qemu-devel] [RFC] linux-user (mostly syscall.c) |
Date: |
Sat, 3 Nov 2007 01:21:23 +0000 |
User-agent: |
Mutt/1.5.16 (2007-06-11) |
Thayne Harbaugh wrote:
> There are several things that I'd like to see addressed in linux-user.
> Some of these are to fix bugs, some are to make qemu linux-user more
> like the Linux kernel, some are to make the internal qemu interfaces
> more consistent.
>
> An internal coding practice that is being addressed bit-by-bit is that
> of managing the interface between the host and the target. Currently
> this is a bit sloppy and inconsistent (some of which I've contributed
> to). There are examples of using target addresses for host pointers and
> host errnos for target errnos, using different types between target and
> host that don't sign-extend properly, as well as other things. This
> causes compiler warnings to actual run-time bugs. Currently I'm
> reviewing all of the linux-user code (mostly syscall.c) to fix these
> inconsistencies. I will be writing developer documentation describing
> the coding practices that should govern the target/host interface and
> submitting patches for the fixes.
>
> As obvious as it may seem I'll re-state that the linux-user emulation is
> emulating the Linux kernel (duh!). There are portions of qemu
> linux-user that are even excerpted directly from the Linux kernel.
> Consequently it is useful for internal qemu data and functions to
> closely mimic the kernel for best code sharing. There are also
> advantages to even structuring qemu directly and file organization in
> similar divisions, groupings and locations. Some of this organization
> might lead to good division so that other user/kernel divisions are
> cleaner (different kernel versions, other OSes - darwin-user and
> others).
>
> Internal qemu interfaces are consistent - except when they aren't. This
> causes coding errors when passing target and host arguments or return
> codes. I'll be documenting the coding practices as well as submitting
> patches to make these consistent. (That sounds a bit redundant with
> other things I've mentioned).
>
> I have about 40 patches already worked up that do this. Some of those
> patches might be broken up smaller. The qemu that we've been working
> with is nearly rock solid (still a few more bugs being wrung out). It
> can nearly build an entire Debian arm distribution for an arm target
> being hosted on x86_64. We're quite excited to get our patches upstream
> so that others can benefit and to ease our maintenance overhead. We're
> also turning our focus to PPC and other archs.
>
> Please let me know if you support the general idea of the coding changes
> above: General clean-up, consistent target/host interfaces, file
> splitting/reorganizing, etc.. In the meantime I'll be putting together
> the developer documentation/coding guidelines for review.
FWIW, I agree with everything you said above.
Thiemo
- [Qemu-devel] [RFC] linux-user (mostly syscall.c), Thayne Harbaugh, 2007/11/02
- Re: [Qemu-devel] [RFC] linux-user (mostly syscall.c),
Thiemo Seufer <=
- Re: [Qemu-devel] [RFC] linux-user (mostly syscall.c), J. Mayer, 2007/11/03
- Re: [Qemu-devel] [RFC] linux-user (mostly syscall.c), Thayne Harbaugh, 2007/11/03
- Re: [Qemu-devel] [RFC] linux-user (mostly syscall.c), Fabrice Bellard, 2007/11/03
- Re: [Qemu-devel] [RFC] linux-user (mostly syscall.c), Thayne Harbaugh, 2007/11/03
- Re: [Qemu-devel] [RFC] linux-user (mostly syscall.c), J. Mayer, 2007/11/03
- Re: [Qemu-devel] [RFC] linux-user (mostly syscall.c), Paul Brook, 2007/11/03
- Re: [Qemu-devel] [RFC] linux-user (mostly syscall.c), J. Mayer, 2007/11/04
Re: [Qemu-devel] [RFC] linux-user (mostly syscall.c), TJ, 2007/11/03