Introduce pci_epf_get_bar_required_size() to retrieve the required BAR
size and memory size. Prepare for adding support to set an MMIO address to
a specific BAR.

Use two variables 'aligned_bar_size' and 'aligned_mem_size' to avoid
confuse.

No functional changes.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
change in v3
- change return value to int.
- use two pointers return bar size aligned and memory start address aligned
- update comments about why need memory align size. Actually iATU require
start address match aligned requirement. Since kernel return align to
size's address.
- use two varible aligned_bar_size and aligned_mem_size to avoid confuse
use 'size'.

change in v2
- new patch
---
 drivers/pci/endpoint/pci-epf-core.c | 84 +++++++++++++++++++++++--------------
 1 file changed, 53 insertions(+), 31 deletions(-)

diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
index d54e18872aefc07c655c94c104a347328ff7a432..2cd0257831f9885a4381c087ed8f3326f5960966 100644
--- a/drivers/pci/endpoint/pci-epf-core.c
+++ b/drivers/pci/endpoint/pci-epf-core.c
@@ -208,6 +208,49 @@ void pci_epf_remove_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf)
 }
 EXPORT_SYMBOL_GPL(pci_epf_remove_vepf);
 
+static int
+pci_epf_get_bar_required_size(struct pci_epf *epf, size_t size,
+			      size_t *aligned_bar_size,
+			      size_t *aligned_mem_size,
+			      enum pci_barno bar,
+			      const struct pci_epc_features *epc_features,
+			      enum pci_epc_interface_type type)
+{
+	u64 bar_fixed_size = epc_features->bar[bar].fixed_size;
+	size_t align = epc_features->align;
+
+	if (size < 128)
+		size = 128;
+
+	/* According to PCIe base spec, min size for a resizable BAR is 1 MB. */
+	if (epc_features->bar[bar].type == BAR_RESIZABLE && size < SZ_1M)
+		size = SZ_1M;
+
+	if (epc_features->bar[bar].type == BAR_FIXED && bar_fixed_size) {
+		if (size > bar_fixed_size) {
+			dev_err(&epf->dev,
+				"requested BAR size is larger than fixed size\n");
+			return -ENOMEM;
+		}
+		size = bar_fixed_size;
+	} else {
+		/* BAR size must be power of two */
+		size = roundup_pow_of_two(size);
+	}
+
+	*aligned_bar_size = size;
+
+	/*
+	 * The EPC's BAR start address must meet alignment requirements. In most
+	 * cases, the alignment will match the BAR size. However, differences
+	 * can occur—for example, when the fixed BAR size (e.g., 128 bytes) is
+	 * smaller than the required alignment (e.g., 4 KB).
+	 */
+	*aligned_mem_size = align ? ALIGN(size, align) : size;
+
+	return 0;
+}
+
 /**
  * pci_epf_free_space() - free the allocated PCI EPF register space
  * @epf: the EPF device from whom to free the memory
@@ -264,40 +307,17 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar,
 			  const struct pci_epc_features *epc_features,
 			  enum pci_epc_interface_type type)
 {
-	u64 bar_fixed_size = epc_features->bar[bar].fixed_size;
-	size_t aligned_size, align = epc_features->align;
+	size_t aligned_mem_size, aligned_bar_size;
 	struct pci_epf_bar *epf_bar;
 	dma_addr_t phys_addr;
 	struct pci_epc *epc;
 	struct device *dev;
 	void *space;
 
-	if (size < 128)
-		size = 128;
-
-	/* According to PCIe base spec, min size for a resizable BAR is 1 MB. */
-	if (epc_features->bar[bar].type == BAR_RESIZABLE && size < SZ_1M)
-		size = SZ_1M;
-
-	if (epc_features->bar[bar].type == BAR_FIXED && bar_fixed_size) {
-		if (size > bar_fixed_size) {
-			dev_err(&epf->dev,
-				"requested BAR size is larger than fixed size\n");
-			return NULL;
-		}
-		size = bar_fixed_size;
-	} else {
-		/* BAR size must be power of two */
-		size = roundup_pow_of_two(size);
-	}
-
-	/*
-	 * Allocate enough memory to accommodate the iATU alignment
-	 * requirement.  In most cases, this will be the same as .size but
-	 * it might be different if, for example, the fixed size of a BAR
-	 * is smaller than align.
-	 */
-	aligned_size = align ? ALIGN(size, align) : size;
+	if (pci_epf_get_bar_required_size(epf, size, &aligned_bar_size,
+					  &aligned_mem_size, bar,
+					  epc_features, type))
+		return NULL;
 
 	if (type == PRIMARY_INTERFACE) {
 		epc = epf->epc;
@@ -308,7 +328,9 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar,
 	}
 
 	dev = epc->dev.parent;
-	space = dma_alloc_coherent(dev, aligned_size, &phys_addr, GFP_KERNEL);
+
+	space = dma_alloc_coherent(dev, aligned_mem_size,
+				   &phys_addr, GFP_KERNEL);
 	if (!space) {
 		dev_err(dev, "failed to allocate mem space\n");
 		return NULL;
@@ -316,8 +338,8 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar,
 
 	epf_bar[bar].phys_addr = phys_addr;
 	epf_bar[bar].addr = space;
-	epf_bar[bar].size = size;
-	epf_bar[bar].aligned_size = aligned_size;
+	epf_bar[bar].size = aligned_bar_size;
+	epf_bar[bar].aligned_size = aligned_mem_size;
 	epf_bar[bar].barno = bar;
 	if (upper_32_bits(size) || epc_features->bar[bar].only_64bit)
 		epf_bar[bar].flags |= PCI_BASE_ADDRESS_MEM_TYPE_64;

-- 
2.34.1

On Thu, Sep 25, 2025 at 01:01:47PM -0400, Frank Li wrote:
> Introduce pci_epf_get_bar_required_size() to retrieve the required BAR
> size and memory size. Prepare for adding support to set an MMIO address to
> a specific BAR.
> 
> Use two variables 'aligned_bar_size' and 'aligned_mem_size' to avoid
> confuse.

s/confuse/confusion/


> 
> No functional changes.
> 
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> change in v3
> - change return value to int.
> - use two pointers return bar size aligned and memory start address aligned
> - update comments about why need memory align size. Actually iATU require
> start address match aligned requirement. Since kernel return align to
> size's address.
> - use two varible aligned_bar_size and aligned_mem_size to avoid confuse
> use 'size'.
> 
> change in v2
> - new patch
> ---
>  drivers/pci/endpoint/pci-epf-core.c | 84 +++++++++++++++++++++++--------------
>  1 file changed, 53 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
> index d54e18872aefc07c655c94c104a347328ff7a432..2cd0257831f9885a4381c087ed8f3326f5960966 100644
> --- a/drivers/pci/endpoint/pci-epf-core.c
> +++ b/drivers/pci/endpoint/pci-epf-core.c
> @@ -208,6 +208,49 @@ void pci_epf_remove_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf)
>  }
>  EXPORT_SYMBOL_GPL(pci_epf_remove_vepf);
>  
> +static int
> +pci_epf_get_bar_required_size(struct pci_epf *epf, size_t size,
> +			      size_t *aligned_bar_size,
> +			      size_t *aligned_mem_size,
> +			      enum pci_barno bar,
> +			      const struct pci_epc_features *epc_features,
> +			      enum pci_epc_interface_type type)
> +{
> +	u64 bar_fixed_size = epc_features->bar[bar].fixed_size;
> +	size_t align = epc_features->align;
> +
> +	if (size < 128)
> +		size = 128;
> +
> +	/* According to PCIe base spec, min size for a resizable BAR is 1 MB. */
> +	if (epc_features->bar[bar].type == BAR_RESIZABLE && size < SZ_1M)
> +		size = SZ_1M;
> +
> +	if (epc_features->bar[bar].type == BAR_FIXED && bar_fixed_size) {
> +		if (size > bar_fixed_size) {
> +			dev_err(&epf->dev,
> +				"requested BAR size is larger than fixed size\n");
> +			return -ENOMEM;
> +		}
> +		size = bar_fixed_size;
> +	} else {
> +		/* BAR size must be power of two */
> +		size = roundup_pow_of_two(size);
> +	}
> +
> +	*aligned_bar_size = size;

I think this name is wrong.
The BAR size has not been aligned to anything.
The BAR size has to be a power of two, but that is a requirement of the PCI
specification, so that in an inherent property of a BAR.

Perhaps just name it size or bar_size?


Kind regards,
Niklas

On Fri, Sep 26, 2025 at 02:31:42PM +0200, Niklas Cassel wrote:
> On Thu, Sep 25, 2025 at 01:01:47PM -0400, Frank Li wrote:
> > Introduce pci_epf_get_bar_required_size() to retrieve the required BAR
> > size and memory size. Prepare for adding support to set an MMIO address to
> > a specific BAR.
> >
> > Use two variables 'aligned_bar_size' and 'aligned_mem_size' to avoid
> > confuse.
>
> s/confuse/confusion/
>
>
> >
> > No functional changes.
> >
> > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > ---
> > change in v3
> > - change return value to int.
> > - use two pointers return bar size aligned and memory start address aligned
> > - update comments about why need memory align size. Actually iATU require
> > start address match aligned requirement. Since kernel return align to
> > size's address.
> > - use two varible aligned_bar_size and aligned_mem_size to avoid confuse
> > use 'size'.
> >
> > change in v2
> > - new patch
> > ---
> >  drivers/pci/endpoint/pci-epf-core.c | 84 +++++++++++++++++++++++--------------
> >  1 file changed, 53 insertions(+), 31 deletions(-)
> >
> > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
> > index d54e18872aefc07c655c94c104a347328ff7a432..2cd0257831f9885a4381c087ed8f3326f5960966 100644
> > --- a/drivers/pci/endpoint/pci-epf-core.c
> > +++ b/drivers/pci/endpoint/pci-epf-core.c
> > @@ -208,6 +208,49 @@ void pci_epf_remove_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf)
> >  }
> >  EXPORT_SYMBOL_GPL(pci_epf_remove_vepf);
> >
> > +static int
> > +pci_epf_get_bar_required_size(struct pci_epf *epf, size_t size,
> > +			      size_t *aligned_bar_size,
> > +			      size_t *aligned_mem_size,
> > +			      enum pci_barno bar,
> > +			      const struct pci_epc_features *epc_features,
> > +			      enum pci_epc_interface_type type)
> > +{
> > +	u64 bar_fixed_size = epc_features->bar[bar].fixed_size;
> > +	size_t align = epc_features->align;
> > +
> > +	if (size < 128)
> > +		size = 128;
> > +
> > +	/* According to PCIe base spec, min size for a resizable BAR is 1 MB. */
> > +	if (epc_features->bar[bar].type == BAR_RESIZABLE && size < SZ_1M)
> > +		size = SZ_1M;
> > +
> > +	if (epc_features->bar[bar].type == BAR_FIXED && bar_fixed_size) {
> > +		if (size > bar_fixed_size) {
> > +			dev_err(&epf->dev,
> > +				"requested BAR size is larger than fixed size\n");
> > +			return -ENOMEM;
> > +		}
> > +		size = bar_fixed_size;
> > +	} else {
> > +		/* BAR size must be power of two */
> > +		size = roundup_pow_of_two(size);
> > +	}
> > +
> > +	*aligned_bar_size = size;
>
> I think this name is wrong.
> The BAR size has not been aligned to anything.
> The BAR size has to be a power of two, but that is a requirement of the PCI
> specification, so that in an inherent property of a BAR.
>
> Perhaps just name it size or bar_size?

there already have 'size' for input.  It should match epc required's size.

how about 'epc_bar_size'?

Frank

>
>
> Kind regards,
> Niklas

On Fri, Sep 26, 2025 at 10:56:46AM -0400, Frank Li wrote:
> On Fri, Sep 26, 2025 at 02:31:42PM +0200, Niklas Cassel wrote:
> > On Thu, Sep 25, 2025 at 01:01:47PM -0400, Frank Li wrote:
> > > Introduce pci_epf_get_bar_required_size() to retrieve the required BAR
> > > size and memory size. Prepare for adding support to set an MMIO address to
> > > a specific BAR.
> > >
> > > Use two variables 'aligned_bar_size' and 'aligned_mem_size' to avoid
> > > confuse.
> >
> > s/confuse/confusion/
> >
> >
> > >
> > > No functional changes.
> > >
> > > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > > ---
> > > change in v3
> > > - change return value to int.
> > > - use two pointers return bar size aligned and memory start address aligned
> > > - update comments about why need memory align size. Actually iATU require
> > > start address match aligned requirement. Since kernel return align to
> > > size's address.
> > > - use two varible aligned_bar_size and aligned_mem_size to avoid confuse
> > > use 'size'.
> > >
> > > change in v2
> > > - new patch
> > > ---
> > >  drivers/pci/endpoint/pci-epf-core.c | 84 +++++++++++++++++++++++--------------
> > >  1 file changed, 53 insertions(+), 31 deletions(-)
> > >
> > > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
> > > index d54e18872aefc07c655c94c104a347328ff7a432..2cd0257831f9885a4381c087ed8f3326f5960966 100644
> > > --- a/drivers/pci/endpoint/pci-epf-core.c
> > > +++ b/drivers/pci/endpoint/pci-epf-core.c
> > > @@ -208,6 +208,49 @@ void pci_epf_remove_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf)
> > >  }
> > >  EXPORT_SYMBOL_GPL(pci_epf_remove_vepf);
> > >
> > > +static int
> > > +pci_epf_get_bar_required_size(struct pci_epf *epf, size_t size,
> > > +			      size_t *aligned_bar_size,
> > > +			      size_t *aligned_mem_size,
> > > +			      enum pci_barno bar,
> > > +			      const struct pci_epc_features *epc_features,
> > > +			      enum pci_epc_interface_type type)
> > > +{
> > > +	u64 bar_fixed_size = epc_features->bar[bar].fixed_size;
> > > +	size_t align = epc_features->align;
> > > +
> > > +	if (size < 128)
> > > +		size = 128;
> > > +
> > > +	/* According to PCIe base spec, min size for a resizable BAR is 1 MB. */
> > > +	if (epc_features->bar[bar].type == BAR_RESIZABLE && size < SZ_1M)
> > > +		size = SZ_1M;
> > > +
> > > +	if (epc_features->bar[bar].type == BAR_FIXED && bar_fixed_size) {
> > > +		if (size > bar_fixed_size) {
> > > +			dev_err(&epf->dev,
> > > +				"requested BAR size is larger than fixed size\n");
> > > +			return -ENOMEM;
> > > +		}
> > > +		size = bar_fixed_size;
> > > +	} else {
> > > +		/* BAR size must be power of two */
> > > +		size = roundup_pow_of_two(size);
> > > +	}
> > > +
> > > +	*aligned_bar_size = size;
> >
> > I think this name is wrong.
> > The BAR size has not been aligned to anything.
> > The BAR size has to be a power of two, but that is a requirement of the PCI
> > specification, so that in an inherent property of a BAR.
> >
> > Perhaps just name it size or bar_size?
> 
> there already have 'size' for input.  It should match epc required's size.

Why do you need both "size_t size" and "size_t *bar_size"?

Isn't it enough with "size_t *bar_size" ?

The user can supply a value, and the function could update that value.


Kind regards,
Niklas

On Fri, Sep 26, 2025 at 05:16:57PM +0200, Niklas Cassel wrote:
> On Fri, Sep 26, 2025 at 10:56:46AM -0400, Frank Li wrote:
> > On Fri, Sep 26, 2025 at 02:31:42PM +0200, Niklas Cassel wrote:
> > > On Thu, Sep 25, 2025 at 01:01:47PM -0400, Frank Li wrote:
> > > > Introduce pci_epf_get_bar_required_size() to retrieve the required BAR
> > > > size and memory size. Prepare for adding support to set an MMIO address to
> > > > a specific BAR.
> > > >
> > > > Use two variables 'aligned_bar_size' and 'aligned_mem_size' to avoid
> > > > confuse.
> > >
> > > s/confuse/confusion/
> > >
> > >
> > > >
> > > > No functional changes.
> > > >
> > > > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > > > ---
> > > > change in v3
> > > > - change return value to int.
> > > > - use two pointers return bar size aligned and memory start address aligned
> > > > - update comments about why need memory align size. Actually iATU require
> > > > start address match aligned requirement. Since kernel return align to
> > > > size's address.
> > > > - use two varible aligned_bar_size and aligned_mem_size to avoid confuse
> > > > use 'size'.
> > > >
> > > > change in v2
> > > > - new patch
> > > > ---
> > > >  drivers/pci/endpoint/pci-epf-core.c | 84 +++++++++++++++++++++++--------------
> > > >  1 file changed, 53 insertions(+), 31 deletions(-)
> > > >
> > > > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
> > > > index d54e18872aefc07c655c94c104a347328ff7a432..2cd0257831f9885a4381c087ed8f3326f5960966 100644
> > > > --- a/drivers/pci/endpoint/pci-epf-core.c
> > > > +++ b/drivers/pci/endpoint/pci-epf-core.c
> > > > @@ -208,6 +208,49 @@ void pci_epf_remove_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf)
> > > >  }
> > > >  EXPORT_SYMBOL_GPL(pci_epf_remove_vepf);
> > > >
> > > > +static int
> > > > +pci_epf_get_bar_required_size(struct pci_epf *epf, size_t size,
> > > > +			      size_t *aligned_bar_size,
> > > > +			      size_t *aligned_mem_size,
> > > > +			      enum pci_barno bar,
> > > > +			      const struct pci_epc_features *epc_features,
> > > > +			      enum pci_epc_interface_type type)
> > > > +{
> > > > +	u64 bar_fixed_size = epc_features->bar[bar].fixed_size;
> > > > +	size_t align = epc_features->align;
> > > > +
> > > > +	if (size < 128)
> > > > +		size = 128;
> > > > +
> > > > +	/* According to PCIe base spec, min size for a resizable BAR is 1 MB. */
> > > > +	if (epc_features->bar[bar].type == BAR_RESIZABLE && size < SZ_1M)
> > > > +		size = SZ_1M;
> > > > +
> > > > +	if (epc_features->bar[bar].type == BAR_FIXED && bar_fixed_size) {
> > > > +		if (size > bar_fixed_size) {
> > > > +			dev_err(&epf->dev,
> > > > +				"requested BAR size is larger than fixed size\n");
> > > > +			return -ENOMEM;
> > > > +		}
> > > > +		size = bar_fixed_size;
> > > > +	} else {
> > > > +		/* BAR size must be power of two */
> > > > +		size = roundup_pow_of_two(size);
> > > > +	}
> > > > +
> > > > +	*aligned_bar_size = size;
> > >
> > > I think this name is wrong.
> > > The BAR size has not been aligned to anything.
> > > The BAR size has to be a power of two, but that is a requirement of the PCI
> > > specification, so that in an inherent property of a BAR.
> > >
> > > Perhaps just name it size or bar_size?
> >
> > there already have 'size' for input.  It should match epc required's size.
>
> Why do you need both "size_t size" and "size_t *bar_size"?
>
> Isn't it enough with "size_t *bar_size" ?
>
> The user can supply a value, and the function could update that value.

If not 'aligned_mem_size' in list, it looks fine. But after add
'aligned_mem_size', I think use difference varible for two outputs will be
clear and consistent and easy to understand.

Frank
>
>
> Kind regards,
> Niklas

On 26 September 2025 19:10:16 CEST, Frank Li <Frank.li@nxp.com> wrote:
>On Fri, Sep 26, 2025 at 05:16:57PM +0200, Niklas Cassel wrote:
>> On Fri, Sep 26, 2025 at 10:56:46AM -0400, Frank Li wrote:
>> > On Fri, Sep 26, 2025 at 02:31:42PM +0200, Niklas Cassel wrote:
>> > > On Thu, Sep 25, 2025 at 01:01:47PM -0400, Frank Li wrote:
>> > > > Introduce pci_epf_get_bar_required_size() to retrieve the required BAR
>> > > > size and memory size. Prepare for adding support to set an MMIO address to
>> > > > a specific BAR.
>> > > >
>> > > > Use two variables 'aligned_bar_size' and 'aligned_mem_size' to avoid
>> > > > confuse.
>> > >
>> > > s/confuse/confusion/
>> > >
>> > >
>> > > >
>> > > > No functional changes.
>> > > >
>> > > > Signed-off-by: Frank Li <Frank.Li@nxp.com>
>> > > > ---
>> > > > change in v3
>> > > > - change return value to int.
>> > > > - use two pointers return bar size aligned and memory start address aligned
>> > > > - update comments about why need memory align size. Actually iATU require
>> > > > start address match aligned requirement. Since kernel return align to
>> > > > size's address.
>> > > > - use two varible aligned_bar_size and aligned_mem_size to avoid confuse
>> > > > use 'size'.
>> > > >
>> > > > change in v2
>> > > > - new patch
>> > > > ---
>> > > >  drivers/pci/endpoint/pci-epf-core.c | 84 +++++++++++++++++++++++--------------
>> > > >  1 file changed, 53 insertions(+), 31 deletions(-)
>> > > >
>> > > > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
>> > > > index d54e18872aefc07c655c94c104a347328ff7a432..2cd0257831f9885a4381c087ed8f3326f5960966 100644
>> > > > --- a/drivers/pci/endpoint/pci-epf-core.c
>> > > > +++ b/drivers/pci/endpoint/pci-epf-core.c
>> > > > @@ -208,6 +208,49 @@ void pci_epf_remove_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf)
>> > > >  }
>> > > >  EXPORT_SYMBOL_GPL(pci_epf_remove_vepf);
>> > > >
>> > > > +static int
>> > > > +pci_epf_get_bar_required_size(struct pci_epf *epf, size_t size,
>> > > > +			      size_t *aligned_bar_size,
>> > > > +			      size_t *aligned_mem_size,
>> > > > +			      enum pci_barno bar,
>> > > > +			      const struct pci_epc_features *epc_features,
>> > > > +			      enum pci_epc_interface_type type)
>> > > > +{
>> > > > +	u64 bar_fixed_size = epc_features->bar[bar].fixed_size;
>> > > > +	size_t align = epc_features->align;
>> > > > +
>> > > > +	if (size < 128)
>> > > > +		size = 128;
>> > > > +
>> > > > +	/* According to PCIe base spec, min size for a resizable BAR is 1 MB. */
>> > > > +	if (epc_features->bar[bar].type == BAR_RESIZABLE && size < SZ_1M)
>> > > > +		size = SZ_1M;
>> > > > +
>> > > > +	if (epc_features->bar[bar].type == BAR_FIXED && bar_fixed_size) {
>> > > > +		if (size > bar_fixed_size) {
>> > > > +			dev_err(&epf->dev,
>> > > > +				"requested BAR size is larger than fixed size\n");
>> > > > +			return -ENOMEM;
>> > > > +		}
>> > > > +		size = bar_fixed_size;
>> > > > +	} else {
>> > > > +		/* BAR size must be power of two */
>> > > > +		size = roundup_pow_of_two(size);
>> > > > +	}
>> > > > +
>> > > > +	*aligned_bar_size = size;
>> > >
>> > > I think this name is wrong.
>> > > The BAR size has not been aligned to anything.
>> > > The BAR size has to be a power of two, but that is a requirement of the PCI
>> > > specification, so that in an inherent property of a BAR.
>> > >
>> > > Perhaps just name it size or bar_size?
>> >
>> > there already have 'size' for input.  It should match epc required's size.
>>
>> Why do you need both "size_t size" and "size_t *bar_size"?
>>
>> Isn't it enough with "size_t *bar_size" ?
>>
>> The user can supply a value, and the function could update that value.
>
>If not 'aligned_mem_size' in list, it looks fine. But after add
>'aligned_mem_size', I think use difference varible for two outputs will be
>clear and consistent and easy to understand.


What am trying to say is:
Why not make "size_t *bar_size" both an input and an output?


Kind regards,
Niklas