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Re: [Qemu-devel] Minor MMU fixes for PowerPC 40x emulation
From: |
Alexander Graf |
Subject: |
Re: [Qemu-devel] Minor MMU fixes for PowerPC 40x emulation |
Date: |
Sat, 2 Oct 2010 18:55:36 +0200 |
On 02.10.2010, at 18:49, John Clark wrote:
>>> /* Check from TLB entry */
>>> - /* XXX: there is a problem here or in the TLB fill code... */
>>> + /* There is no longer a need to force PAGE_EXEC permission
>>> here */
>>> + /* because of the tlb->attr fix in helper_4xx_tlbwe_lo() */
>>
>> I guess that comment is superfluous, as readers several years from now don't
>> care what was broken back in the day :).
>
> Yes, I suppose so :)
>
>>> @@ -3939,7 +3939,7 @@ target_ulong helper_4xx_tlbre_lo (target_ulong entry)
>>> tlb = &env->tlb[entry].tlbe;
>>> ret = tlb->EPN;
>>> if (tlb->prot & PAGE_VALID)
>>> - ret |= 0x400;
>>> + ret |= 0x40; /* V bit is 0x40, not 0x400 */
>>
>> Ouch. Mind to make it a define?
>
> Sure, I was surprised that there wasn't a define for that when I found it.
The ppc emulation code lacks a lot of defines. In fact, the same goes for x86
emulation too ;). But that doesn't mean we have to keep it that way!
>
>>> size = booke_page_size_to_tlb(tlb->size);
>>> if (size < 0 || size > 0x7)
>>> size = 1;
>>> @@ -3948,7 +3948,7 @@ target_ulong helper_4xx_tlbre_lo (target_ulong entry)
>>> return ret;
>>> }
>>>
>>> -target_ulong helper_4xx_tlbre_hi (target_ulong entry)
>>> +target_ulong helper_4xx_tlbre_lo (target_ulong entry)
>>
>> Huh?
>
> To summarize, 'tlbre' has two forms: one to retrieve the high bits of
> a TLB entry (TLBHI), and one to retrieve the low bits (TLBLO) of a TLB
> entry. This code had the TLBLO form returning the bits corresponding
> to TLBHI and vice versa, hence the name change. You can verify this
> if you like with this IBM PowerPC 405 core user manual on page 362:
Well the thing that strikes me as weird is mostly that you're changing a
function name, but no callers to it. So is this function never used? Or was
tlbre_lo defined before already and is now defined twice?
Alex
PS: Please use the "reply to all" function of your mailer. Others might be
interested in the reply too :).
- [Qemu-devel] Minor MMU fixes for PowerPC 40x emulation, John Clark, 2010/10/02
- Re: [Qemu-devel] Minor MMU fixes for PowerPC 40x emulation, Alexander Graf, 2010/10/02
- Message not available
- Re: [Qemu-devel] Minor MMU fixes for PowerPC 40x emulation,
Alexander Graf <=
- Re: [Qemu-devel] Minor MMU fixes for PowerPC 40x emulation, John Clark, 2010/10/02
- Re: [Qemu-devel] Minor MMU fixes for PowerPC 40x emulation, Edgar E. Iglesias, 2010/10/02
- Re: [Qemu-devel] Minor MMU fixes for PowerPC 40x emulation, Alexander Graf, 2010/10/02
- Re: [Qemu-devel] Minor MMU fixes for PowerPC 40x emulation, John Clark, 2010/10/02
- Re: [Qemu-devel] Minor MMU fixes for PowerPC 40x emulation, Alexander Graf, 2010/10/05
- Re: [Qemu-devel] Minor MMU fixes for PowerPC 40x emulation, Edgar E. Iglesias, 2010/10/05