[ISSUE] Default x86_64 kernel allows only 4 serial ports.

[ISSUE] Default x86_64 kernel allows only 4 serial ports.

[wb4kdi]

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New issue by wb4kdi on void-packages repository

https://github.com/void-linux/void-packages/issues/49598

Description:
### Is this a new report?

Yes

### System Info

Void 6.6.22 x86_64 Glibc

### Package(s) Affected

linux6.6 

### Does a report exist for this bug with the project's home (upstream) and/or another distro?

Ubuntu kernel : Serial: 8250/16550 driver, 32 ports, IRQ sharing enabled

### Expected behaviour

in dmesg: Serial: 8250/16550 driver, 32 ports, IRQ sharing enabled

### Actual behaviour

in dmesg: Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled

### Steps to reproduce

Install a 4 or 8 port PCIe serial card to use for process control. Can use only the first four or only 3 if the system includes a legacy serial device.

Re: [ISSUE] [CLOSED] Default x86_64 kernel allows only 4 serial ports.

[wb4kdi]

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Closed issue by wb4kdi on void-packages repository

https://github.com/void-linux/void-packages/issues/49598

Description:
### Is this a new report?

Yes

### System Info

Void 6.6.22 x86_64 Glibc

### Package(s) Affected

linux6.6 

### Does a report exist for this bug with the project's home (upstream) and/or another distro?

Ubuntu kernel : Serial: 8250/16550 driver, 32 ports, IRQ sharing enabled

### Expected behaviour

in dmesg: Serial: 8250/16550 driver, 32 ports, IRQ sharing enabled

### Actual behaviour

in dmesg: Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled

### Steps to reproduce

Install a 4 or 8 port PCIe serial card to use for process control. Can use only the first four or only 3 if the system includes a legacy serial device.

Re: Default x86_64 kernel allows only 4 serial ports.

[wb4kdi]

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New comment by wb4kdi on void-packages repository

https://github.com/void-linux/void-packages/issues/49598#issuecomment-2027865707

Comment:
The limit of 4 "legacy" serial ports is archaic and really no longer applies to modern 64 bit systems.  Kernel config entries CONFIG_SERIAL_8250_NR_UARTS=48 and
CONFIG_SERIAL_8250_RUNTIME_UARTS=32 is what is used for Ubuntu.  The user can change the limit of available RUNTIME serial ports with the 8250.nr_uarts=x kernel variable.  nr_uarts cannot be more than the max set with  CONFIG_SERIAL_8250_NR_UARTS.