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Re: [Qemu-devel] [PATCH] target-arm: Move VLD/VST multiple into helper f
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH] target-arm: Move VLD/VST multiple into helper functions |
Date: |
Sat, 4 Jun 2011 11:01:20 +0100 |
On 3 June 2011 21:47, Aurelien Jarno <address@hidden> wrote:
> Does this patch fixes a real issue (ie most probably a crash), or it is
> just to make the arm target compliant with the README?
I haven't actually generated a test case which would make qemu
abort, but it shouldn't be hard to do so.
> Two remarks there:
> - The guidance in tcg/README is probably true for complex helpers in the
> sense of doing a lot of logic/arithmetic operations for which the TCG
> instruction set if not really rich and for which the compiler can do
> a lot better. When the instruction is emulated mostly by load/store
> ops, there isn't much possible optimizations left.
Yes. The 96 op limit to avoid overrunning the buffer is a hard
one, though.
> - Your patch calls the slow version of the _mmu functions, which doesn't
> use the QEMU TLB. It is therefore normal to expect a slow down.
...even for linux-user mode? That doesn't use softmmu...
Anyway, this patch is on my list to rework when I can figure
out what the right approach to it is.
-- PMM