| Message ID | 20250320223002.2915728-18-pierrick.bouvier@linaro.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | single-binary: start make hw/arm/ common | expand |
On 3/20/25 15:29, Pierrick Bouvier wrote: > We introduce later a mechanism to skip cpu definitions inclusion, so we > can detect it here, and call the correct runtime function instead. > > Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org> > --- > include/exec/target_page.h | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/include/exec/target_page.h b/include/exec/target_page.h > index 8e89e5cbe6f..aeddb25c743 100644 > --- a/include/exec/target_page.h > +++ b/include/exec/target_page.h > @@ -40,6 +40,9 @@ extern const TargetPageBits target_page; > # define TARGET_PAGE_MASK ((TARGET_PAGE_TYPE)target_page.mask) > # endif > # define TARGET_PAGE_SIZE (-(int)TARGET_PAGE_MASK) > +# ifndef TARGET_PAGE_BITS_MIN > +# define TARGET_PAGE_BITS_MIN qemu_target_page_bits_min() > +# endif > #else > # define TARGET_PAGE_BITS_MIN TARGET_PAGE_BITS > # define TARGET_PAGE_SIZE (1 << TARGET_PAGE_BITS) Mmm, ok I guess. Yesterday I would have suggested merging this with page-vary.h, but today I'm actively working on making TARGET_PAGE_BITS_MIN a global constant. r~
On 3/21/25 11:05, Richard Henderson wrote: > On 3/20/25 15:29, Pierrick Bouvier wrote: >> We introduce later a mechanism to skip cpu definitions inclusion, so we >> can detect it here, and call the correct runtime function instead. >> >> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org> >> --- >> include/exec/target_page.h | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/include/exec/target_page.h b/include/exec/target_page.h >> index 8e89e5cbe6f..aeddb25c743 100644 >> --- a/include/exec/target_page.h >> +++ b/include/exec/target_page.h >> @@ -40,6 +40,9 @@ extern const TargetPageBits target_page; >> # define TARGET_PAGE_MASK ((TARGET_PAGE_TYPE)target_page.mask) >> # endif >> # define TARGET_PAGE_SIZE (-(int)TARGET_PAGE_MASK) >> +# ifndef TARGET_PAGE_BITS_MIN >> +# define TARGET_PAGE_BITS_MIN qemu_target_page_bits_min() >> +# endif >> #else >> # define TARGET_PAGE_BITS_MIN TARGET_PAGE_BITS >> # define TARGET_PAGE_SIZE (1 << TARGET_PAGE_BITS) > > Mmm, ok I guess. Yesterday I would have suggested merging this with page-vary.h, but > today I'm actively working on making TARGET_PAGE_BITS_MIN a global constant. > When you mention this, do you mean "constant accross all architectures", or a global (const) variable vs having a function call? > > r~
On 3/21/25 11:09, Pierrick Bouvier wrote: >> Mmm, ok I guess. Yesterday I would have suggested merging this with page-vary.h, but >> today I'm actively working on making TARGET_PAGE_BITS_MIN a global constant. >> > > When you mention this, do you mean "constant accross all architectures", or a global > (const) variable vs having a function call? The first -- constant across all architectures. r~
On 3/21/25 12:27, Richard Henderson wrote: > On 3/21/25 11:09, Pierrick Bouvier wrote: >>> Mmm, ok I guess. Yesterday I would have suggested merging this with page-vary.h, but >>> today I'm actively working on making TARGET_PAGE_BITS_MIN a global constant. >>> >> >> When you mention this, do you mean "constant accross all architectures", or a global >> (const) variable vs having a function call? > The first -- constant across all architectures. > That's great. Does choosing the min(set_of(TARGET_PAGE_BITS_MIN)) is what we want there, or is the answer more subtle than that? I went through that question, and was not sure what should be the answer. > > r~
On 3/21/25 13:11, Pierrick Bouvier wrote: > On 3/21/25 12:27, Richard Henderson wrote: >> On 3/21/25 11:09, Pierrick Bouvier wrote: >>>> Mmm, ok I guess. Yesterday I would have suggested merging this with page-vary.h, but >>>> today I'm actively working on making TARGET_PAGE_BITS_MIN a global constant. >>>> >>> >>> When you mention this, do you mean "constant accross all architectures", or a global >>> (const) variable vs having a function call? >> The first -- constant across all architectures. >> > > That's great. > Does choosing the min(set_of(TARGET_PAGE_BITS_MIN)) is what we want there, or is the > answer more subtle than that? It will be, yes. This isn't as hard as it seems, because there are exactly two targets with TARGET_PAGE_BITS < 12: arm and avr. Because we still support armv4, TARGET_PAGE_BITS_MIN must be <= 10. AVR currently has TARGET_PAGE_BITS == 8, which is a bit of a problem. My first task is to allow avr to choose TARGET_PAGE_BITS_MIN >= 10. Which will leave us with TARGET_PAGE_BITS_MIN == 10. r~
On 3/21/25 15:19, Richard Henderson wrote: > On 3/21/25 13:11, Pierrick Bouvier wrote: >> On 3/21/25 12:27, Richard Henderson wrote: >>> On 3/21/25 11:09, Pierrick Bouvier wrote: >>>>> Mmm, ok I guess. Yesterday I would have suggested merging this with page-vary.h, but >>>>> today I'm actively working on making TARGET_PAGE_BITS_MIN a global constant. >>>>> >>>> >>>> When you mention this, do you mean "constant accross all architectures", or a global >>>> (const) variable vs having a function call? >>> The first -- constant across all architectures. >>> >> >> That's great. >> Does choosing the min(set_of(TARGET_PAGE_BITS_MIN)) is what we want there, or is the >> answer more subtle than that? > > It will be, yes. > > This isn't as hard as it seems, because there are exactly two targets with > TARGET_PAGE_BITS < 12: arm and avr. > > Because we still support armv4, TARGET_PAGE_BITS_MIN must be <= 10. > > AVR currently has TARGET_PAGE_BITS == 8, which is a bit of a problem. > My first task is to allow avr to choose TARGET_PAGE_BITS_MIN >= 10. > > Which will leave us with TARGET_PAGE_BITS_MIN == 10. > Ok. From what I understand, we make sure tlb flags are stored in an immutable position, within virtual addresses related to guest, by using lower bits belonging to address range inside a given page, since page addresses are aligned on page size, leaving those bits free. bits [0..2) are bswap, watchpoint and check_aligned. bits [TARGET_PAGE_BITS_MIN - 5..TARGET_PAGE_BITS_MIN) are slow, discard_write, mmio, notdirty, and invalid mask. And the compile time check we have is to make sure we don't overlap those sets (would happen in TARGET_PAGE_BITS_MIN <= 7). I wonder why we can't use bits [3..8) everywhere, like it's done for AVR, even for bigger page sizes. I noticed the comment about "address alignment bits", but I'm confused why bits [0..2) can be used, and not upper ones. Are we storing something else in the middle on other archs, or did I miss some piece of the puzzle? Thanks, Pierrick > > r~
On 3/21/25 17:01, Pierrick Bouvier wrote: > On 3/21/25 15:19, Richard Henderson wrote: >> On 3/21/25 13:11, Pierrick Bouvier wrote: >>> On 3/21/25 12:27, Richard Henderson wrote: >>>> On 3/21/25 11:09, Pierrick Bouvier wrote: >>>>>> Mmm, ok I guess. Yesterday I would have suggested merging this with page-vary.h, but >>>>>> today I'm actively working on making TARGET_PAGE_BITS_MIN a global constant. >>>>>> >>>>> >>>>> When you mention this, do you mean "constant accross all architectures", or a global >>>>> (const) variable vs having a function call? >>>> The first -- constant across all architectures. >>>> >>> >>> That's great. >>> Does choosing the min(set_of(TARGET_PAGE_BITS_MIN)) is what we want there, or is the >>> answer more subtle than that? >> >> It will be, yes. >> >> This isn't as hard as it seems, because there are exactly two targets with >> TARGET_PAGE_BITS < 12: arm and avr. >> >> Because we still support armv4, TARGET_PAGE_BITS_MIN must be <= 10. >> >> AVR currently has TARGET_PAGE_BITS == 8, which is a bit of a problem. >> My first task is to allow avr to choose TARGET_PAGE_BITS_MIN >= 10. >> >> Which will leave us with TARGET_PAGE_BITS_MIN == 10. >> > > Ok. > > From what I understand, we make sure tlb flags are stored in an > immutable position, within virtual addresses related to guest, by using > lower bits belonging to address range inside a given page, since page > addresses are aligned on page size, leaving those bits free. > > bits [0..2) are bswap, watchpoint and check_aligned. > bits [TARGET_PAGE_BITS_MIN - 5..TARGET_PAGE_BITS_MIN) are slow, > discard_write, mmio, notdirty, and invalid mask. > And the compile time check we have is to make sure we don't overlap > those sets (would happen in TARGET_PAGE_BITS_MIN <= 7). > > I wonder why we can't use bits [3..8) everywhere, like it's done for > AVR, even for bigger page sizes. I noticed the comment about "address > alignment bits", but I'm confused why bits [0..2) can be used, and not > upper ones. > > Are we storing something else in the middle on other archs, or did I > miss some piece of the puzzle? > After looking better, TLB_SLOW_FLAGS are not part of address, so we don't use bits [0..2). For a given TARGET_PAGE_SIZE, how do we define alignment bits? > Thanks, > Pierrick > >> >> r~ >
diff --git a/include/exec/target_page.h b/include/exec/target_page.h index 8e89e5cbe6f..aeddb25c743 100644 --- a/include/exec/target_page.h +++ b/include/exec/target_page.h @@ -40,6 +40,9 @@ extern const TargetPageBits target_page; # define TARGET_PAGE_MASK ((TARGET_PAGE_TYPE)target_page.mask) # endif # define TARGET_PAGE_SIZE (-(int)TARGET_PAGE_MASK) +# ifndef TARGET_PAGE_BITS_MIN +# define TARGET_PAGE_BITS_MIN qemu_target_page_bits_min() +# endif #else # define TARGET_PAGE_BITS_MIN TARGET_PAGE_BITS # define TARGET_PAGE_SIZE (1 << TARGET_PAGE_BITS)
We introduce later a mechanism to skip cpu definitions inclusion, so we can detect it here, and call the correct runtime function instead. Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org> --- include/exec/target_page.h | 3 +++ 1 file changed, 3 insertions(+)