On 11/4/07, J. Mayer <[EMAIL PROTECTED]> wrote: > > On Sun, 2007-11-04 at 09:12 +0200, Blue Swirl wrote: > > On 11/4/07, Fabrice Bellard <[EMAIL PROTECTED]> wrote: > > > Blue Swirl wrote: > > > > Hi, > > > > > > > > RISC CPUs don't support self-modifying code unless the affected area > > > > is flushed explicitly. This patch disables the extra effort for SMC. > > > > The changes in this version would affect all CPUs except x86, but I'd > > > > like to see if there are problems with some target, so that the > > > > committed change can be limited. Without comments, I'll just disable > > > > SMC for Sparc, as there are no problems. So please comment, especially > > > > if you want to "opt in". > > > > > > > > For some reason, I can't disable all TB/TLB flushing, for example > > > > there was already one line with TARGET_HAS_SMC || 1, but removing the > > > > || 1 part causes crashing. Does anyone know why? > > > > > > With the current QEMU architecture, you cannot disable self-modifying > > > code as you did. This is why I did not fully supported the > > > TARGET_HAS_SMC flag. The problem is that the translator make the > > > assumption that the RAM and the TB contents are consistent for example > > > when handling exceptions. Suppressing this assumption is possible but > > > requires more work. > > > > I think the conclusion is that we would need some kind of emulator for > > i-cache for any accurate emulation. And handling the boot loader may > > need an uncached mode. > > > The performance benefit from disabling SMC is unnoticeable according > > to my benchmarks. Adding a TB flush to i-cache flushing made things > > worse. Moreover, SMC is hardly ever used on Sparc. > > > > I'll just commit the debug statement fixes and > > > the fix that separates > > PAGE_READ from PAGE_EXEC for Sparc. > > This patch is absolutely not needed. You have to directly call > tlb_set_page_exec instead of tlb_set_page if you want to separate > PAGE_READ from PAGE_EXEC. > #ifdef TARGET_xxx should never occur in generic code and in that > specific case, it's the Sparc target code that has to be fixed...
In fact Sparc code calls only tlb_set_page_exec, never tlb_set_page, so no fix is necessary. This reminds me that there is some TARGET_SPARC conditional code in fdc.c, I'll change those.